Premorbid functioning seems to be a phenomenological marker that possibly distinguishes a subtype of schizophrenia. The Premorbid Adjustment Scale (PAS) is an instrument for measuring premorbid functioning. It has gained international acceptance, although little is known about the reliability and validity of the test. Here data on the reliability and validity of the test derived from a German sample of schizoaffective and schizophrenic subjects (n = 86) and their healthy parents (n = 38) is presented. The DSM-IV diagnosis, PAS and Positive and Negative Syndrome Scale (PANSS) data were used as well as data on the course of the disorder. The estimation of the reliability per scale by internal consistency showed high positive values of Cronbach's alpha between 0.809 and 0.931. High scores in PAS representing a bad premorbid social adjustment correlated significantly with a low age of onset, high PANSS scores, an insidious onset and a long period of hospitalisation. The disorganised DSM-IV subtype of schizophrenia showed a trend towards higher mean PAS scores. In the presented sample, the threshold between schizophrenics and healthy individuals is at 0.23. The PAS values higher than 0.53 appeared in patients with an unfavourable course of the disorder. These findings correspond with previous reports in the literature.