The estimation of total nitrogen, nonprotein nitrogen, urea, creatinine in sera on 27 patients of prostatic hypertrophy was carried out. The patients stated above were divided into two groups, the one has been received the hormone therapy and the other has not been received it. 1. Total nitrogen, generally, decreased after the prostatectomy, but in hormone therapy group, it was increased until one week after the operation. 2. Nonprotein nitrogen over 40 mg/dl at preoperation could be found in 44.4% (12 in 27 patients). In hormone therapy group, N. P. N. increased until one week after the operation and many cases showed high levels and unrest values. 3. Urea, in general, paralleled to N. P. N. and creatinine showed normal value in most cases. 4. In the cases of renal insufficiency, the nitrogen component in sera showed much differences at the operation and the effects of hormone should be considered generally.