The present prospective follow-up study of 163 schizophrenic patients admitted to hospital for the first time examined the relationship between premorbid adjustment and different measures of the 3-year course and outcome. The same instruments had been used in all phases of the study. The Premorbid Adjustment Scale was used to assess premorbid social functioning. Outcome measures were positive symptoms, negative symptoms, social disability and number of rehospitalizations. The results of the multiple regression analyses showed that premorbid adjustment was the strongest overall predictor of outcome. Premorbid adjustment was significantly associated with negative symptoms and social disability over the 3-year course of illness. In a further step, we examined the relationship between good, moderate and poor premorbid adjustment and the course of positive symptoms, negative symptoms and social disability within the first 3 years after index admission. The most important finding was that premorbid functioning showed a stronger correlation with the course of negative symptoms and social disability than with the course of positive symptoms. Poor premorbid social functioning implies a poor social course of the illness. Female subjects showed better premorbid functioning than male subjects. Good premorbid adjustment was strongly associated with an acute onset of the illness, and poor premorbid adjustment with an insidious onset.