The purpose of this article was to explore sexual knowledge in persons who had suffered from myocardial infarction (MI). Seventy-six Swedish persons completed the "Sex after MI Knowledge Test" questionnaire. Overall, 53% of the men and 45% of the women scored maximum in the test. In a comparison between sexes, the men scored significantly more often a correct answer compared to the women for two out of the 25 items. The levels of correct answers were less then 50% for 14 out of the 25 items in both sexes. In conclusion we found that people who had suffered MI had poor levels of knowledge about sex and that there were some differences concerning lesser knowledge among the females in comparison to males. In regard to application, using a validated instrument facilitates an interactive communication between the patient and health care professionals, and opens up for a tailored education in line with the patient's and his or her partner's needs.