Renal lymphangiomatosis is an unusual disorder. It may develop due to the abnormality of the intrarenal, peripelvic and perirenal lymphatics. The differential diagnosis contains renal lymphoma, polycystic kidney disease, multicystic dysplasia and renal tumors. We report a case of renal lymphangiomatosis, previously diagnosed as autosomal dominant polycystic kidney disease, to emphasize that these two diseases can be easily confused. It should be kept in mind that RL is in the differential diagnosis of polycystic renal disease to prevent overtreatment.