Abstract: Ohmefentanyl (OMF) is a new μ opioid receptor agonist with high affinity and selectivity, and possesses anesthetic activity. With radioimmunoassay, the plasma levels of cortisol(C), corticosterone (CS) and antidiuretic hormone (ADH) in rats were measured. The results indicated that no significant differences in the plasma C, CS and ADH levels were observed between the saline control group and the OMF- treated group. Trauma (bone-crush injury) increased significantly the plasma CS level. However, pretreatment with OMF 4.0 μg·kg^-1 reduced markedly the CS plasma levels in trauma treated rats. The results suggest that OMF anesthesia itself showed no obvious effect on the plasma concentration of C, CS and ADH, but blocked the hormoral stress responses such as the increment of plasma CS level caused by trauma stimulus.