Of 48 canine primary renal neoplasms found in the files of the Armed Forces Institute of Pathology, 36 were of tubular cell origin (five adenomas and 31 carcinomas), six of transitional cell origin (two papillomas and four carcinomas), two were nephroblastomas and four were nonepithelial. With the exception of nephroblastomas, renal neoplasms occurred in dogs older than 5 years and were most common in males. No breed predilection was apparent. Eight of the neoplasms were classified by histologic criteria as benign and 40 as malignant. Seventeen of the malignant neoplasms had metastasized. The neoplasms of tubular cell origin contained solid, tubular and papillary patterns, often mixed within the same tumor.