Management of candiduria is limited by the lack of information about its natural history and lack of data from controlled studies on the efficacy of treating it with antimycotic agents. We compared fungal eradication rates among 316 consecutive candiduric (asymptomatic or minimally symptomatic) hospitalized patients treated with fluconazole (200 mg) or placebo daily for 14 days. In an intent-to-treat analysis, candiduria cleared by day 14 in 79 (50%) of 159 receiving fluconazole and 46 (29%) of 157 receiving placebo (P<.001), with higher eradication rates among patients completing 14 days of therapy (P<.0001), including 33 (52%) of 64 catheterized and 42 (78%) of 54 noncatheterized patients. Pretreatment serum creatinine levels were inversely related to candiduria eradication. Fluconazole initially produced high eradication rates, but cultures at 2 weeks revealed similar candiduria rates among treated and untreated patients. Oral fluconazole was safe and effective for short-term eradication of candiduria, especially following catheter removal. Long-term eradication rates were disappointing and not associated with clinical benefit.