Fifteen Indian patients with relapsing or drug-refractory visceral leishmaniasis were retreated for 30 days with antimony plus interferon-gamma (IFN-gamma). All 15 had failure of an initial course of antimony and at least one additional course of antimony or pentamidine; 7 patients had failure of three or four prior courses of therapy. During the study, treatment was discontinued in 2 patients because of anemia and congestive heart failure in 1 and intractable vomiting in the other; both subsequently died. In the remaining 13 patients, IFN-gamma plus antimony treatment was associated with daily fever but no other adverse reactions. After 30 days of therapy, 9 (69%) of the 13 patients were apparently cured. Six months after treatment, all 9 were healthy, had parasite-free bone marrow aspirate smears, and were considered cured. None have relapsed during a mean follow-up of 15.9 +/- 1.7 months. These results support the use of antimony plus IFN-gamma as an immunochemotherapeutic alternative for kala-azar patients who have repeated failures of conventional treatment.