The testing of anabolizer utilization in cattle farming needs quick, sure and cheap detection techniques. The administration of oestrogen to cattle produces hypertrophy of the prostate, bulbourethral glands and urethral muscle. The aim of this study was to quantify the effect of the association of zeranol (an hormonomimetic drug acting as an oestrogen) and trembolone (a steroidic structure originating from testosterone) on the urethral muscle of bull calves which is easy to sample in the slaughter-house. An histoenzymological and morphometric study of the urethral muscle of 90 bull calves that had been treated showed considerable hypertrophy in transversal sections of the muscle fibers that was increased by more than 90% in the two main types of striated muscle fiber. The morphological method used is proposed for monitoring the meat of untreated bull calves, requested by a class of consumers.