Prostate glands from 40 canines aged 5 years or greater, submitted to the Histopathology Laboratory ofthe San Marcos University Faculty ofVeterinary Medicine, were studied. Macroscopic evaluation was made, the glands were measured (length and width in cm) and weighed (g), and the age and body weight ofthe animals recorded. Histological sections of external (Corpus prostatae) and interna] parts (Pars disseminata prostatae) related to the urethral lumen ofthe glands, were prepared using hematoxylin, eosin, Picro Ponceau, Manson trichrome and Van Gieson stains. Microscopic evaluation revealed hyperplastic, inflammatory, degenerative and neoplastic alterations. Hyperplastic processes were found in 33 ofthe 40 cases (82.5%), with glandular hyperplasia present in 12 cases (36%) and cystic glandular hyperplasia in 21 cases ( 64%). Inflammatory processes (chronic non-suppurative prostatitis) were observed in 12.5% (5/40) ofthe glands. One degenerative process case (2.5%) was diagnosed as glandular atrophy and one neoplastic process case (2.5%) was diagnosed as adenocarcinoma. The prostate weight (gr)/ body weight (kg) ratio ranged between 0.62 and 8.32 in the hyperplastic cases, between 0.85 and 1. 90 in the inflammatory alterations, was of 0.60 in the atrophy case and 1.65 in the neoplastic alteration. Twelve specimens showed bladder hypertrophy, corresponding to 30% (12/40) ofthe cases studied.