This study aimed to examine whether a dose-response relationship exists between psychological distress and types of physical activity (total, occupational, and leisure-time). The study subjects (233 men and 313 women) were recruited for a study on cardiovascular disease in the Yangpyeong community located in South Korea. The type and characteristics of physical activity were measured with a modified version of the Stanford 5 city project's questionnaire by well-trained interviewers using a standard protocol. The Psychological Well-being Index-Short Form was used to assess psychological distress. Both the intensity and duration of time in either total physical activity or occupational physical activity (OPA) were not related to the distress score. However, a long duration of time (1 hr/day) in severely intensive (> or =6 metabolic equivalent) OPA was related to a high distress score in men (14.1 for none vs. 19.7, p-for-trend=0.005), even after the adjustment for leisure-time physical activity (LTPA). A long duration in time (1 hr/day) in LTPA was related to a lower distress score in men independent of their OPA (16.7 for none vs. 13.1, p-for-trend=0.02). In conclusion, the dose-response relationship of physical activity on psychological distress appeared to differ among the different types of activities. The type of activity may be an important determinant of whether physical activity produces psychological benefits.