Background In the 1980s, it was observed that people living farther from the Equator had a higher incidence of cardiovascular disease. Whether sunlight explains this finding is unknown. MethodsWe analyzed more than 180 countries' age-standardized average cholesterol, agestandardized mean systolic blood pressure, age-standardized prevalence of raised blood pressure, and death rate from ischemic heart disease, by geographic latitude. In addition to latitude, we performed analysis by ultraviolent B light exposure averaged over several years.We assessed for changes in these relationships in men and in women using data from several decades. Results Age-standardized mean cholesterol in men and in women increases with the distance of their country from the Equator. This relationship has changed very little since 1980.Similarly, in 1975, the mean systolic blood pressure and the prevalence of raised blood pressure were higher in countries farther from the Equator. However, the relationship between latitude and blood pressure has changed dramatically, such that by 2015, the opposite pattern was observed in women. The relationship between latitude and countries' rate of ischemic heart disease has changed in a manner tracking the changes in blood pressure. Countries' average ultraviolet B light exposure has a stable relationship with cholesterol over recent decades, but has a changing relationship with blood pressure. Conclusions Since sunlight exposure in a country averaged over several years is relatively fixed and since its relationship with blood pressure has changed dramatically in recent decades, countries' average sunlight exposure is an unlikely explanation for contemporary country-level variation in blood pressure. However, our findings are consistent with a putative effect of sunlight on countries' average cholesterol, as well as a no longer detectable effect on blood pressure decades ago. A parsimonious potential explanation for the relationship between light and cholesterol is that 7-dehydrocholesterol can be converted to cholesterol, or in the presence of ultraviolet light, it can instead be converted to vitamin D. Nonetheless, other explanations can be hypothesized.