Clinical and haematological changes occuring in rams with experimental urethral obstruc¬tion included the following:¬ 1-A lowered body temperature postoperation. In the contrary pulse and respiration were acelerated. 2-Blood haemoglobin content and P.C.V.values decreased with severity of uraemia. Res¬pective values up to 6,5 gm/100 ml and 17% for P.C.V, were recorded at time of death. No correlation between total leucocyte count and severity of uraemia was achieved