A renal epithelial tumor with a papillary or tubulopapillary pattern and a low nuclear grade is defined as a renal adenoma if its diameter is 5 mm or less. Two important issues related to the renal adenoma are the lack of exact criteria for the histopathological differentiation from a papillary renal cell carcinoma and the lack of consensus as to whether it is a precancerous lesion. Renal adenomatosis is very rarely seen entity entity characterized by multiple and usually bilateral adenomas. Innumerable adenomas, adenomatous transformations within a single tubule and adenomas measuring 7 mm or less, were detected in a 47-year-old man who underwent simple nephrectomy due to nonfunctional hydronephrosis secondary to urolithiasis. In this paper, our diagnostic approach to this fairly rare entity is discussed along with a brief literature review.