Background: Gender differences among patients with coronary artery disease vary from study to study. In one of the largest studies, the Japanese Coronary Artery Disease (JCAD) Study, gender differences in patients were investigated. Methods and Results: Consecutive patients diagnosed with stenosis 75% or more in at least one branch of the coronary arteries were enrolled in the study. The endpoint is a composite of all-cause death and cardiovascular events. Data were collected over the internet. Out of 15,628 patients screened, 13,812 of them met the inclusion criteria and were followed up for a mean period of 2.7 years. The event rate was 62.8 per 1,000 patients-year, all-cause death 17.3 and total cardiac events 47.4. The incident rate of unstable angina was higher in females (27.1) than males (21.8) (P=0.0363). The incidence of all-cause death was lower in females than males (16.9 and 17.8, respectively; P=0.0148). Other than gender, hypertension and number of vessel disease contribute to the event of unstable angina, and age, family history, obesity, impaired fasting glycemia, hyperlipidemia, congestive heart failure and number of vessel disease contribute to the all-cause death. Conclusions: Gender is an independent contributing factor of unstable angina and of all-cause death. (Circ J 2009; 73: 912 - 917)