Blood samples and physiological data were collected from 634 bighorn sheep captured between 1980 and 1986 in the western United States. Bighorn sheep were evaluated for physiological parameters (temperature, pulse and respiration), selected biochemical parameters (Cortisol, creatine phosphokinase (CPK), serum glutamic oxaloacetic transaminase (SGOT), lactic dehydrogenase (LDH), alkaline phosphotase (AP), potassium, sodium, chloride, creatinine, blood urea nitrogen (BUN), selenium, glucose, total protein, plasma pH and plasma P_CO2), and selected hematological parameters (packed cell volume (PCV), hemoglobin (HB), red blood cell count (RBC), and white blood cell count (WBC)). These parameters were compared among bighorn sheep captured by four different methods: drop-net (n = 158), drive-net (n = 249), chemical immobilization (n =90) and the net-gun (n = 137). Biological parameters affected by stress, including temperature, respiration, Cortisol, CPK, SGOT, potassium, glucose and WBC revealed significant differences among capture methods (P < 0.05). Some blood parameter differences, including temperature, respiration, Cortisol, glucose and WBC could be explained partially by the distribution of age and sex within capture method groups. Drop-net and net-gun methods of capture appeared to produce the least amount of alteration to biological parameters related to capture stress or compromise and capture mortality. Drive-net was similar to the former methods while chemical immobilization caused the greatest changes in the above physiological, biochemical and hematological parameters.