Temocillin, a new beta-lactamase-stable penicillin, was administered in a dosage of 2g twice daily to 25 biliary surgery patients in whom potential septic complications were a concern. Clinical efficacy was assessed as 'very good' in 23 patients. In one patient there was a disorder of wound healing and in another a staphylococcal bronchial pneumonia developed postoperatively. Temocillin was tolerated very well, and no side effects were observed. 12 hours after administration of temocillin 2g intravenously to surgical patients the mean serum concentration was 22.44 (+/- 10.26) mg/L. The median half-life was 3.86 hours (+/- 1.84) hours. Mean concentrations of 12.44 and 38.59 mg/L were measured up to the twelfth hour in the wound secretions and peritoneal secretions, respectively. In skin, fat, fascia, muscle and gallbladder wall, temocillin concentrations greater than the inhibitory concentrations of most Gram-negative bacteria were demonstrated after 1 and 2 hours.