Between May 1, 1988 and January 1, 1990, 10 patients were treated for Candida peritonitis. Origins of the infections were lesions and perforations of the gastrointestinal tract. Risk factors promoting the disease were tumours, diabetes mellitus and extensive antibiotic therapy. The mean classification by the APACHE score 2 was 19.0. All patients underwent the programmed peritoneal lavage for diffuse peritonitis. Daily relaparotomy and lavage of all quadrants of the abdomen was performed. The diagnosis of Candida peritonitis had been established by microbiological investigation, increasing serologic titres, histologic demonstration of a deep mycosis and clinical picture. All patients were treated with 300 mg fluconazole daily. Five of the ten patients died from their severe primary diseases in spite of control of fungal peritonitis. Daily relaparotomies allowed to follow up the microbiologic and histologic course of the disease. Within 2 to 4 days after administration of fluconazole, hydrous swelling and reduction of fungal elements could be demonstrated histologically. On the 4th day after onset of antifungal therapy, fungal mycelia were markedly reduced and distendedly decayed. Fluconazole clearly leads to a destruction of deeply invading Candida elements within 4 days.