We report the chemotherapeutic effect of itraconazole in chronic chagasic patients. The efficacy of treatment was analyzed by xenodiagnosis (XD), conventional serology (CS) and antibody dependent-complement mediated lysis test (CoML). Twenty chronic chagasic persons from endemic areas of Chile were grouped according to the results of xenodiagnosis (XD) performed before therapy. The follow-up of patients was performed at an average time of 42 months after treatment. No significative statistical differences were observed in the result of ELISA and Indirect Immunofluorescence test performed on serq before and after therapy with itraconazole. In the group of patients with positive XD before therapy, sera from six of them displayed lytic activity against Trypanosoma cruzi. The lytic activity of only one of these sera became negative after therapy. In relation to XD, five of those patients showed a positive tests at least once during the follow-up period. In the group of ten patients with negative XD before therapy, sera from eight of them displayed lytic activity. At the end of the follow-up period seven of them became negative. Nine of the ten patients maintained their original condition with respect to XD. These results suggests that parasitaemia level before therapy condition could be an important parameter to consider in the chemotherapy of chronic Chagas disease.