Eighty-two current and former UC officers used by the department between 1969 and 1981 were administered a survey consisting of 121 items believed to be related to stress among UC officers before, during, and after the UC assignment. The study indicates that a variety of psychiatric symptomatology was associated with the assumption and performance of undercover policing duties, and these symptoms persisted after the undercover assignment ended. The symptoms most commonly reported by the subjects were anxiety, loneliness/isolation, oversuspiciousness, and relationship/marital problems. Stepwise multiple regression anaylsis identified the following factors as principally related to the symptoms: isolation due to not being able to talk with others about the assignment and major changes in marital and other significant relationships. The second study focused on the 68 former UC officers still with the department. This study hypothesized that these former UC officers would commit a greater number of infractions than officers who had no UC experience. Chi square analysis on each disciplinary category did not suport the hypothesis. The findings indicate that stress on UC officers could be relieved through the improved selection, training, supervision, and reintegration of such officers. 7 data tables and 7 references.