Abstract Recent figures show that more than 30 000 people suicide each year in Japan, and that many of them are considered to suffer from depression. In addition, the suicide rate among Japanese women has been shown to be higher than in other countries. However, it is not clear whether the psychiatric symptoms leading to suicide differ by gender. The authors examined gender differences in psychiatric symptoms related to suicidal ideation (SI) in Japanese patients with depression. Study subjects were 199 new patients (66 men and 133 women) who were diagnosed with a major depressive disorder. SI and psychiatric symptoms were assessed by several psychological tests using questionnaires. Logistic regression analysis was used to calculate the odds ratio (OR) and 95% confidence interval (CI) with an adjustment for all relevant factors simultaneously. The stepwise method was also used for selecting variables. In univariate analysis, several psychosocial factors such as self-reproach, derealization, depressive moods, depersonalization, and anxiety traits were statistically significantly associated with SI in both men and women. However, multivariate analysis using the stepwise method distinguished gender differences. Low social/family support and depersonalization were statistically significantly associated with SI in men, while depressive moods and an anxiety state were significantly associated with SI in women. The relation between derealization and SI was statistically significant in women but not significant in men.