Pediatricians have reported benign hematuria owing to focal glomerulitis of unknown cause in children with normal blood pressure and glomerular filtration rates. Because a few reports have suggested that a similar benign syndrome occurs in adults, we undertook a prospective and retrospective study of 21 patients, ages 14 to 41 years, who initially fulfilled the following criteria: recurrent or persistent gross or microscopic hematuria, normal blood pressure, normal serum creatinine level and creatinine clearance, 24-hour urine protein excretion not exceeding 1 g, absence of known causes of glomerulonephritis or nonglomerular causes of hematuria, and renal biopsy changes of focal, local glomerular hypercellularity. Eighteen patients were reevaluated 0.83 to 11 years after the first episode of hematuria. Of these, 13 had persistent hematuria, but in only 1 patient had 24-hour protein excretion risen, from 790 mg to 2.2 g. Five of those re-evaluated had normal urinalyses and protein excretion. In all patients reevaluated blood pressure, serum creatinine levels and creatinine clearance were normal. The short-term prognosis (2 to 10 years) is therefore excellent for adults with hematuria, minimal proteinuria, and idiopathic focal glomerulitis who have normal blood pressure and renal function.