Different drugs have been used as adjuvant to neuroleptics in chronic schizophrenia. Bromocriptine, carbamazepine and cyproheptadine have shown an efficacy added to neuroleptics in schizophrenia. In our study, 24 chronic schizophrenic inpatients considered to be resistant to neuroleptics were treated double blind with the associations haloperidol (40 mg a day)--carbamazepine (400 mg a day), haloperidol (40 mg a day)--bromocriptine (2.5 mg a day), haloperidol (40 mg a day)--cyproheptadine (24 mg a day) and haloperidol (40 mg a day)--placebo. The drugs were given successively, in a randomized succession using a latin square procedure, for four 5-weeks periods. A psychiatric assessment using the Brief Psychiatric Rating Scale (BPRS), the SANS (Scale for Assessment of Negative Symptoms) and the SAPS (Scale for Assessment of Positive Symptoms) occurred every two weeks. Extrapyramidal symptomatology and abnormal movements were assessed using the AIMS (Abnormal Involuntary Movement Scale) and the Simpson-Angus scale. Using an ANOVA, we cannot show any clinical efficacy of any of those three drugs as an adjuvant to haloperidol. The discrepancy between our results and the data of the literature can be linked to the high specificity of our sample (resistance to neuroleptics). We cannot show any specific efficacy of those drugs on positive and negative symptoms, using the sub-factors of the SAPS and SANS.