The efficacies of cilofungin (Ly121019), a semisynthetic lipopeptide antifungal agent, and amphotericin B in the treatment of disseminated candidiasis in normal and neutropenic mice were compared. In mice infected with 2 x 10(6) CFU of Candida albicans, treatment with cilofungin in twice-daily doses of 25 or 35 mg/kg of body weight by intraperitoneal injection for 10 days gave survival rates of 83 and 90%. In contrast, there was 97% mortality in infected controls receiving 2 x 10(6) CFU intravenously and 93% survival in mice treated with 1 mg of amphotericin B per kg once a day. Mice rendered granulocytopenic by the administration of cyclophosphamide showed survival rates of 83 and 80% when treated with 25 or 35 mg of cilofungin per kg for 10 days compared with 43% survival rate in mice treated with 1 mg of amphotericin B per kg (P = 0.0030 and P = 0.0080, respectively). Similar results were obtained when the two antifungal agents were administered for a period of 30 days. Administration of 25 or 35 mg of cilofungin per kg twice a day to granulocytopenic mice receiving 10(6) CFU of C. albicans gave survival rates of 93% and 93% compared with 53% survival with amphotericin B. With 15 mg of cilofungin per kg twice a day for 10 days, a survival rate of 43 to 50% was observed in both normal and granulocytopenic mice compared with 56 and 60%, respectively, when this dosage was continued for 30 days. Cilofungin eradicated C. albicans from the kidneys, spleens, and livers of surviving animals. No toxic effects were observed with any of the dosage regimens used. The clearance of C. albicans from the kidneys, spleens, livers, and brains in normal mice was studied following infection with 5 x 10(5) and 1 x 10(5) intravenously. The mice in the treatment groups received 25 mg of cilofungin per kg twice a day for 10 days. In 8 to 12 days, this treatment was able to clear the organisms from the kidneys, spleens, and livers of mice infected with 5 x 10(5) C. albicans. Mice infected with 10(5) C. albicans and treated with cilofungin (25 mg/kg) twice a day for 10 days had no organisms in the kidney, spleen, and liver at days 8, 2, and 8, respectively. There was 1-log-unit reduction in C. albicans counts in brain tissue from mice of one of the treated groups between 2 h and 2 days postinfection, after which the numbers of organisms remained the same until day 12. These data demonstrate the efficacy of cilofungin in the treatment of disseminated C. albicans infections in normal and granulocytopenic mice. The treatment regimen used in this study was able to clear C. albicans from the kidneys, spleen, and liver but not from brain tissue.