Surgical interventions produce a stress response in patients. Electrostimulation analgesia (ESA) has been described as a method yielding excellent results in poor-risk patients. The present study was undertaken to investigate the stress response of ESA compared with neuroleptanalgesia (NLA). 30 female patients (16 with ESA, 14 with NLA) ranging from 34 to 55 years without endocrine, hepatic, renal or cardiovascular disease who were undergoing vaginal hysterectomy, were subjected to the study. The concentrations of cortisol, cholesterol and glucose in the plasma, the mean arterial blood pressure, the heart rate and the tension-time-index were measured before and during anesthesia as well as during and after surgery. In patients receiving ESA the stress reaction seems to be more pronounced, judged by the higher level of plasma cortisol. The decrease of cholesterol as well as the increase of plasma glucose, mean arterial pressure, heart rate and tension-time-index supported this interpretation. During anaesthesia but before starting the operation the changes in the parameters showed that ESA induces a higher stress reaction than NLA.