The role of trypsin as a hormone-like substance in animals and human is extremely relevant in searching for pharmaceutical drugs to optimize metabolisms. Trypsin is currently undeservedly forgotten and rarely used in veterinary and medical practice. it should also be remembered that crystalline trypsin has a side effect, since its intramuscular injection is painful. In the present work, we evaluated blood morphobiochemical and blood circulation parameters in rabbits intramuscularly injected with trypsin diluted with physiological solution or lidocaine. Experiments were performed by the groupperiod method. All animals were divided into 3 groups. Group 1 (control) received 0.5 ml intramuscular trypsin (0.25 mg/kg bodyweight) diluted with saline S (0.01 g trypsin + 5.0 ml PS). Group 2 received 0.5 ml intramuscular trypsin (0.25 mg/kg bodyweight) diluted with 2.0 % lidocaine/ Group 3 was injected with 0.5 ml of 2 % lidocaine. There were three periods in each experiment. Prior to treatments, we measured blood arterial pressure (BP) using a petMAP graphic II tonometer (Ramsey Medical, Inc., USA), heart rate (HR) and respiratory rate (RR) by the phonendoscopy method. After the injections, BP, HR and RR were measured immediately, and we repeatedly measured these parameters 30 min after intramuscular injections. The results showed that the effect of trypsin on blood circulation in rabbits resulted from a decrease in heart rate, regardless of the diluent. This effect is stronger with lidocaine because lidocaine itself can reduce heart rate. Crystal trypsin diluted with saline and injected intramuscularly increases blood trypsin activity by 14.1 % compared to the control (p < 0.05). When trypsin is diluted with lidocaine to reduce the pain response to injection, several blood biochemical parameters change which is presumably a lidocaine effect. Glucose concentration decreases by 61.1 % (p < 0.05), triglycerides by 30.0 % (p < 0.05), alkaline phosphatase activity by 32.2 % (p < 0.05) vs. control. There were no significant changes if saline was a diluent. Therefore, lidocaine as a diluent for crystalline trypsin affects blood parameters that are involved to energy metabolism. This can reduce the positive effect of trypsin on metabolism in animals.