One hundred forty three pairs of cancer patients and healthy controls were enrolled in this study. Thirty four psychologic stress factors were analyzed by stepwise and logistic regressions to identify risk factors for cancer. At the level of significance of alpha = 0.05, F(10,120) = 1.91 and alpha = 0.01, F(10,120) = 2.47, 15 and 13 risk factors were entered into stepwise regression equation, respectively. By conditioned logistic regression analysis, the following five major correlated factors were revealed: introversive personality, family accidents, the ten-year turmoil, repeated mishaps and death of children. The results indicate that, among all the psychological stress factors studied, introversive personality is the most important predisposing factor in the causation of cancer. This study suggests that psychologic stress might play important part in the etiopathogenesis of human malignancies.