A preliminary study demonstrated that psychiatric patients' evaluation of their work behaviour was unrelated to assessments made by experienced supervisors. Patients involved in clerical work were shown to be more accurate in self-assessment than patients in the manual assembly section of a rehabilitation unit; clerical patients underestimated, and manual patients overestimated their performance. These findings were confirmed in a second study, which also identified some of the differences between the 'clerical' and 'manual' groups, and showed that underestimation was associated with higher intelligence, a general tendency to admit to undesirable behaviours, and a relatively long period of contact with psychiatric services. Neuroticism was also related to underestimation, and schizophrenic patients overestimated their performance. Work satisfaction was found to be unrelated to work performance.