This study, based in a psychiatric hospital, reviews the incidence of breast cancer in 93 patients who had received phenothiazines prior to developing breast cancer compared with a control group of 28 patients who did not receive phenothiazines. The results indicate no significant difference in the incidence of breast cancer between those patients receiving phenothiazines and those that did not. The retrospective study covered a period of 21 years. The overall incidence of breast cancer in 63,000 female patients was found to be 1.85/1,000 as compared with 2/1,000 in the general population.