The effects of acute surgical stress and the accompanying anesthesia on anterior pituitary function in female subjects was studied by means of frequent perioperative determinations of the circulating concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin (PRL), growth hormone (GH), and thyroid-stimulating hormone (TSH). No appreciable alteration in the circulating concentrations of either LH or FSH could be detected. In contrast, the levels of PRL and GH were found to be markedly increased during the perioperative period, with the increase in pRL invariably preceding any noticeable alteration in GH levels. In addition, perioperative PRL but not GH levels were significantly higher (p < 0.01) in patients undergoing a major surgical procedure, in contrast to a minor one. Finally, this study furnishes detailed evidence of a small but significant (p < 0.05) increase in TSH levels in patients undergoing a major surgical procedure. These data indicate that augmentation of pituitary secretion of three stress-related hormones, but not gonadotropins, occurs during surgical procedures.