A study by Michigan State University found that older men who had sex once a week or more were twice as likely to have cardiovascular episodes five years later than men who were not sexually active.
But women who participated in the study and who said they found sex to be extremely pleasurable or satisfying were found to be at lower risk of hypertension.
Hui Liu, associate professor of sociology at the university, said: "These findings challenge the widely held assumption that sex brings uniform health benefits to everyone."
The study, which researchers claim is the first large-scale study into how sex affects heart health in later life, surveyed 2,204 people aged 57-85 between 2005-2006, and then again five years later.
The findings are published in Journal of Health and Social Behaviour.
