Changes in physiological and biochemical parameters after administration of medetomidine (MED), midazolam (MID), ketamine (KET) and a 2% of the inhalation anesthetic sevoflurane (SEVO), were investigated in domestic chickens. The anesthetic protocol began with a simultaneous intrapectoral injection (IP) of MED (50 mu g/kg) and MID (0.5 mg/kg), followed by IP administration of 25 mg/kg of KET 10 min later. Anesthesia was then maintained for 30 min by 2% SEVO (with a 500 ml/min oxygen flow), using an Ayres T piece device. Heart and respiratory rates, cloacal temperature, reflex response and electrocardiogram (ECG) parameters were recorded at time zero (T0) before anesthesia (BA, baseline values), at time of MED + MID administration (T1), at time of ketamine injection (T2), 30 min after the start of SEVO inhalation (T3) and at recovery. Blood was also drawn at T0 and T3 to assess albumin, creatinine, glucose and liver enzyme concentrations. Cloacal temperature, heart and respiratory rates differed from baseline values at all time intervals during anesthesia (p < 0.05). Heart rate decreased following the MED + MID injection (at T1, T2 and T3), and partially recovered by the reanimation period. Reflex response also differed between time 0 and all anesthesia time points (p < 0.05). Mean amplitude of the P wave of the ECG was increased during MED + MID (T1) and KET (T2) anesthesia. The mean ST interval showed a large increase at T1, which was maintained throughout anesthesia (p < 0.05). Albumin, glucose and the ALT enzyme decreased between T0 and T3. In conclusion, the use of MED + MID + KET and SEVO as an anesthetic combination altered card ioresp ratory and biochemical parameters of chickens, but no life-threatening effects were observed as a result of these changes. Hence, this drug combination can be adequately used as an anesthesia protocol in chickens.