We reported 29 kidneys with angiomyolipoma in 23 patients (14 women and 9 men). One of these cases was associated with tuberous sclerosis. Their age ranged from 20 to 82 years (mean 48.9). Six patients had bilateral renal involvement and 7 had multiple lesions in one kidney. Synchronous renal tumors were noted in three patients. One patient was associated with renal cell carcinoma, and the other two patients with transitional cell carcinoma. Nineteen tumors in 16 patients were larger than 4 cm. Among them 93.8% (15/16 patients) were symptomatic and tumor hemorrhage was found in 57.9% (11/19 kidneys). Of these patients, 17 renal units underwent surgical intervention (including 8 total nephrectomy, 7 partial nephrectomy and 2 enucleation of tumor). Preoperative diagnosis was made in 82.4% (14/17) with combined imaging of sonogram and CT scan. One patient received embolization only. There were two mortalities: one patient with tumor rupture who received emergent nephrectomy but died of irreversible hypovolemic shock, and the other with tuberous sclerosis and pulmonary fibrosis who received embolization for spontaneous rupture of tumor but expired due to respiratory failure. Among nine patients receiving renal preserving operation, the post-operative effective renal plasma flow of the affected kidneys ranged from 96 to 184 ml/min (mean 131.7 ml/min). There was no evidence of recurrence during a mean followup of 2.6 years. Eight asymptomatic patients with 9 renal masses had incidental angiomyolipoma and did not undergo exploration. We did not note any progression of the lesions in the cases under observation for a mean followup of 2.6 years.(ABSTRACT TRUNCATED AT 250 WORDS)