21 of 41 patients developed clinically manifest or systemic Candida albicans infection 1-36 months after renal transplantation. Asymptomatic candiduria was diagnosed in all patients even before the onset of clinical symptoms. Fungal stomatitis was the most frequent clinical sign, followed by mycotic changes in the respiratory, genito-urinary (vaginitis) and gastro-intestinal tract. In five cases intrahepatic biliary stasis was diagnosed in the course of a Candida albicans septicaemia. In 12 patients with renal transplants it was possible, by treatment with nystatin, clotrimazole, flucytosine, miconazole and amphotericine B to control a generalized or clinically manifest Candida albicans infection. Three died of the septicaemia or meningoencephalitis, six as the result of bacterial superinfections. Inspection of the mouth is an important means of early diagnosing fungal infections. Antimycotic treatment should be started if fungal cultures from urine are repeatedly positive even if the clinical findings are still negative.