An open label trial was conducted to study the efficacy of zuclopenthixol decanoate, a D1/D2 antagonist, in the treatment of chronic (> 10 years) neuroleptic-resistant aggressive schizophrenia (n = 10) and psychotic oligophrenic patients (n = 6). A significant reduction was noted in the Brief Psychiatric Rating Scale score, especially in the clusters of hostility-suspiciousness and excitement. After many years of seclusion, ten of the 16 patients were transferred to an open psychiatric department and were allowed to visit their families.