Atypical neuroleptics are increasingly used in the treatment of bipolar and schizoaffective disorders. Currently, numerous controlled short-term studies are available for clozapine, olanzapine, risperidone or quetiapine, but long-term data are still missing. Three patients (2 with bipolar disorder, 1 with schizoaffective disorder) are described who showed a marked reduction of affective symptomatology after clozapine had been added to mood stabilizer pretreatment. The patients were seen once a month before and after the introduction of clozapine for at least 6 months. Treatment response was evaluated using different rating scales (IDS, YMRS; GAF; CGIBP) and the NIMH Life Chart Methodology. All patients showed a marked improvement after the add-on treatment with clozapine had been initiated. Clozapine was tolerated well with only transient and moderate weight gain and fatigue as only side effects. This case series underlines the safety and efficacy of clozapine as add-on medication in the treatment of bipolar and schizoaffective disorders. Copyright (C) 2002 S. Karger AG, Basel.