Leading Causes of Death in the World

The leading cause of death in the world is the same as in the United States: heart disease. The World Health Organization counted 9.1 million deaths from ischaemic heart disease in 2021, the most recent year in its Global Health Estimates. That is about 13 percent of all deaths on earth, which makes it the single biggest killer of people worldwide.^[1]

This page covers the global number one, the full top ten, how the world's list differs from the American one, and why a rich country and a poor country do not die of the same things. The WHO's most recent complete estimates are for 2021, a year still shaped by COVID-19. Every figure carries its year and links to its source.

Ischaemic heart disease, the coronary artery disease that also leads in the United States. The WHO counted 9.1 million deaths from it in 2021, about 13 percent of all deaths worldwide, and it has held the top spot for more than twenty years. Deaths from it rose by 2.7 million between 2000 and 2021.^[1]

Total deaths worldwide in 2021 were 68 million. The ten leading causes together accounted for 39 million of them, or 57 percent. Seven of those ten are noncommunicable diseases, the chronic conditions of aging populations rather than infections.^[1]

Here are the ten leading causes of death worldwide in 2021, ranked, from the WHO's Global Health Estimates. Where the WHO publishes a death count, it is shown; where it publishes only a share of total deaths, that is shown instead:^[1][2]

1. Ischaemic heart disease: 9.1 million
2. COVID-19: 8.8 million
3. Stroke: about 10 percent of all deaths
4. Chronic obstructive pulmonary disease (COPD): about 5 percent of all deaths
5. Lower respiratory infections: 2.5 million
6. Trachea, bronchus and lung cancers: 1.9 million
7. Alzheimer disease and other dementias: 1.8 million
8. Diabetes mellitus
9. Kidney diseases
10. Hypertensive heart disease

Two of the lower ranks are worth naming. Diabetes reached the top ten after its death toll rose 95 percent since 2000. Kidney disease climbed from the world's nineteenth leading cause of death to the ninth over the same period, one of the fastest rises on the list.^[1] The tenth cause, hypertensive heart disease, is the damage chronic high blood pressure does to the heart itself. Counted separately from the ischaemic heart disease at the top of the list, it means two of the world's ten deadliest conditions are forms of heart disease.

In 2021, COVID-19 was the second leading cause of death in the world, directly responsible for 8.8 million deaths. Its arrival pushed most other leading causes down one place that year, so stroke, COPD, and the rest each ranked one lower than they had before the pandemic.^[1]

That number is for a single year at the height of the pandemic. In a normal year, stroke is the world's second leading cause of death, and COVID-19 recedes down the list as the pandemic fades. The 2021 estimate is the most recent complete year the WHO has published, so it still shows COVID-19 near the top.

The very top of both lists is the same: heart disease is number one in the world and number one in the United States. Below that, the two lists diverge. The American list is almost entirely chronic, noncommunicable disease: heart disease, cancer, accidents, stroke, and chronic lung disease fill the top five. The global list still carries infections high up, with lower respiratory infections at number five and COVID-19 at number two in 2021.^[1][3]

Cancer is where the ranking looks most different, and the difference is mostly bookkeeping. In the US, all cancers are counted together as one cause, which puts cancer second nationally, with 619,876 deaths in 2024.^[3] The WHO splits cancer by the part of the body it starts in, so lung cancer alone ranks sixth worldwide at 1.9 million, and the other cancers sit lower on their own lines.^[1] Counted the same way, cancer is a leading cause in both places.

This is where the global picture splits hardest. In low-income countries, eight of the top ten causes of death in 2021 were communicable diseases, the infections that wealthy countries mostly stopped dying from decades ago. Malaria, tuberculosis, and HIV and AIDS all remained in the low-income top ten. Even COVID-19 ranked only sixth in those countries, where it killed 258,000 people, because so many people were already dying of other things first.^[1]

In high-income countries, deaths concentrate in noncommunicable disease and rise as populations age. Heart disease, stroke, cancers, and dementia dominate, while infections and the conditions of early life fall off the list. The same disease that leads both lists, heart disease, is reached by very different routes: in rich countries through decades of aging, in poor countries alongside infections that still kill people young.

Heart disease leads in nearly every country because the things that cause it are nearly everywhere: high blood pressure, tobacco, poor diet, and inactivity, plus the plain fact of getting older. As countries grow wealthier and people live longer, infections kill fewer of them, and more people survive to the age when coronary artery disease becomes fatal. Heart disease rises to the top as a country develops, not as it declines.

Much of that toll is preventable. The WHO reports that ischaemic heart disease deaths rose by 2.7 million between 2000 and 2021, driven largely by risk factors that respond to blood pressure control, tobacco reduction, and diet.^[1] That is why it is both the world's biggest killer and one of the causes public health spends the most effort trying to move.

The WHO's Global Health Estimates pull together death registration data, surveys, and statistical models from countries around the world, then apply one consistent set of coding rules so the numbers can be compared across borders. Each death is assigned a single underlying cause, the condition that started the chain of events, the same method national statistics offices use.^[2]

The most recent complete year in the estimates is 2021. Global figures lag further behind than any single country's, because the WHO has to wait for data from many countries and fill gaps where registration is incomplete. That is why the current worldwide ranking is still 2021, while the United States already has final 2024 data of its own.^[1][3]

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This page is death education, not medical advice. Figures are the World Health Organization's Global Health Estimates for 2021 and the CDC's 2024 final US data; see our Sources and Methodology. For how the same causes rank inside the United States, and by age, see Leading Causes of Death in America and Leading Causes of Death by Age.