Halofantrine study on uncomplicated falciparum malaria patients was carried out at ITCI hospital in Balikpapan, East Kalimantan, Indonesia in 1990-1991. This study was conducted to compare the efficacy and safety of halofantrine on in vitro sensitive and resistant chloroquine falciparum malaria patients. Of the 80 patients selected according to WHO criteria for in vivo and in vitro drug sensitivity test and treated orally with 500 mg halofantrine 6 hourly for 3 doses, only 46 patients could be further analized as the in vitro sensitive group (19) and resistant group (27). On admission, no significant different findings were noted in characteristics, clinical symptoms and signs, hematological and biochemical parameters between the sensitive and resistant groups except thrombocyte and creatinine. Clinical symptoms more frequently encountered were headache (92,6-100%), fever (789- 92,6%), chills (78,9-85,2%) and nausea or/and vomiting (57,9-63%). There were no significant differences between the sensitive and resistant groups in cure rate (100% and 96,3%), fever clearance time (17,1 ± 3,5 h and 21,8 ± 4,6 h) and parasite clearance time (51,6 ± 2,8 h and 66,9 ± 12,1 h). When the patients were discharged, the hematological and biochemical parameters showed normal values, except thrombocyte, but the differences between those groups were insignificant. This study showed that halofantrine is effective and safe both for treatment on in vitro sensitive chloroquine falciparum malaria patients and for treatment on in vitro resistant chloroquine falciparum malaria patients.