Ketoconazole suspension (20 mg per ml) was compared with nystatin (100,000 units per ml) in the treatment of oral candidosis in newborns and infants. In all patients Candida infection was proven by culture. Twenty patients were treated with ketoconazole and 15 patients with nystatin. Treatment was discontinued 2 days after clinical cure, or after 3 weeks. The investigator assessed the severity of the thrush and accompanying symptoms at the start of the study and at weekly controls. After one week all 20 patients on ketoconazole (100%) and 8 (53%) patients on nystatin were cured clinically. At the end of the treatment 12 patients on nystatin (80%) were cured. Clinical cure was confirmed by negative culture in 94% of the patients on ketoconazole and in 73% of the patients on nystatin. No side-effects were observed in the patients on ketoconazole. Only in the case of one patient on nystatin, was vomiting observed. This study shows that ketoconazole cures thrush faster and more effectively than nystatin.