A retrospective study is presented of prostatic diseases diagnosed in 32 dogs over a period of 26 years in a private veterinary practice.Of the 32 diseased dogs, 19 patiens were aged 6-10 years, 11 dogs were 11-15 years of age, and 2 animals were younger than 5 years.An unusual case of prostate carcinoma in a 2-year-old Dobermann is documented.Based on clinical, radiographic and ultrasonographic examination completed by bacteriological and laboratory tests, prostatitis was diagnosed in 6 animals.In 26 dogs prostatic hyperplasia was found by rectal examination, and elevated serum acid phosphatase concentration indicated neoplasms.Hormone therapy (Cyproteronacetate, Diethylstilbestrol) was used in 21 dogs with hyperplastic prostate for 4 weeks.However, four months later all dogs were castrated as hyperplasia reoccurred.Castrationresulted in a permanent improvement in ca 40% of patients.Hyperplasia tended to diminish after castration, and in material collected 6 months later by fineneedle transurethral bopsy, carcinoma was still diagnosed in 3 dogs.Our findings confirm more frequent prostatic diseased in aged dogs.Occurrence and frequency of prostatic tumours in dogs can be ascribed to hormonal dysbalance.Hormone therapy cannot cure the malignancies but may bring relief.Castration is the method of choice.