Release from proactive inhibition (RPI) in first-episode (FE) schizophrenic patients and the potential of RPI as a genotypic marker of schizophrenia was investigated in two studies. The first study showed that FE patients ( n=35) exhibited weaker RPI than matched obsessive compulsive disorder (OCD) patients (n=20) as well as healthy controls (n=34). OCD patients and controls showed similar RPI. The second study showed that RPI is similar in both parents of patients (n=64) and matched controls (n=52). Results were explained in terms of additional evidence for impairment in the inhibition of irrelevant information in schizophrenia. Combination of our data and literature review suggests that diminished RPI can be attributed to a combination of dorsolateral-prefrontal and dorsomedial-thalamic impairment. RPI may not be a genotypic marker for schizophrenia but rather related to the illness or its treatment. An alternative explanation in terms of insufficient power of the parent-sample, due to unilineal inheritance of schizophrenia is, however, possible.