Clindamycin, a semi-synthetic antibiotic of the lincomycin family, at a dose of 450 mg eight-hourly for three days in adults cured five out of 10 patients moderately ill with chloroquine-resistant falciparum malaria. Combination therapy with full-dose quinine and clindamycin for three days cured all four patients so treated who were followed up, and with half dosage three out of five patients were cured. Both combinations, however, caused upper gastrointestinal toxicity and appeared to potentiate both toxicity and possibly antimalarial efficacy. Colitis due to clindamycin was not observed. Sequential therapy was not toxic and could be useful in patients who have relapsed after more conventional treatment.