The number of female doctors in Japan has been increasing, but the relationship between their work environment and their mental health is not clear. This study aimed to determine factors in the work environment influencing mental health status among female doctors. We mailed an anonymous survey questionnaire to 587 female doctors, and 367 (62.5%) responded. The survey included questions about age, marital status, work-related information including their specialty, affiliated medical facility, position, type of employment, working time, and night duty. The thirty-item version of the General Health Questionnaire (GHQ-30) was used to examine psychological distress. For the purposes of analysis, subjects with a GHQ-30 score greater than or equal to eight were considered to have psychological distress. The mean age of the subjects was 45.1 yr (SD 15.1). A total of 152 [corrected] (41.6% [corrected]) of subjects met criteria for having psychological distress. Bivariate analysis showed that age (p=0.0009), marital status (p=0.0038), medical facility (p=0.0476), position (p=0.0180), working time (p=0.0337), and working at night (p<0.0001) were associated with the GHQ-30 score. Multiple logistic regression analysis showed that younger age (p=0.0030), engaging in night duty (p=0.0049), and being divorced (p=0.0093) were independently associated with psychological distress. These results suggest that work environment factors, particularly night duty, play important roles in modulating psychological distress among female doctors.