Approximately 40%-70% of neuroleptic-resistant schizophrenic patients are nonresponders even to clozapine. Several clozapine augmentation strategies have come into clinical practice, although often without evidence-based support. This study aims to critically review all the reported case studies regarding the efficacy and safety of adjunctive agents in clozapine-resistant schizophrenic or schizoaffective patients. All published case studies examining the efficacy and safety of adjunctive agents in clozapine-resistant schizophrenic patients were searched for in the MEDLINE database from January 1980 to February 2004. Case studies regarding ECT as a clozapine augmentation strategy were not included in our study. All the included papers were critically reviewed and examined against a set of clinical and pharmacological parameters, outcome measures, and reported side effects. Fifteen case studies regarding the efficacy and safety of sulpiride, risperidone, olanzapine, lithium, lamotrigine, fluvoxamine, and bromocriptine as clozapine adjuncts were found. A total of 33 schizophrenic or schizoaffective patients were included. Of the 15 studies, 8 were associated with risperidone. The duration and dosage of previous clozapine monotherapy was adequate for 16 patients. Plasma clozapine level was assessed for only 7 patients. Outcome measures were used for only 11 patients. The outcome was positive in 13 studies. Combined treatments were generally well tolerated, and side effects never resulted in discontinuation of treatment. Most case studies favor the use of risperidone as an adjunctive agent in clozapine-resistant schizophrenic or schizoaffective patients. However, small numbers of patients and other methodological shortcomings limit the impact of evidence provided.