Little is known of the temporal and quantitative relationships between emptying of the stomach and of the gall bladder in patients with duodenal ulcer before and after vagotomy. A non-invasive double isotope technique was used to investigate these relationships in 27 patients with a duodenal ulcer, before and after operation-truncal vagotomy and pyloroplasty (TV + P; n = 15) and highly selective vagotomy (HSV; n = 12). A further 25 patients were studied after operation (TV + P, n = 20: HSV, n = 5). 99Tcm-EHIDA was used as the biliary tracer and 113Inm bran as the gastric content tracer. In patients with a duodenal ulcer before surgery and in 16 of the 17 patients studied after HSV, the patterns of gall bladder emptying were similar to those previously found in normal subjects. In 60% of patients after TV + P, patterns of gall bladder emptying were altered and the onset of gall bladder emptying was significantly delayed (p less than 0.001) compared with unoperated patients and patients with a HSV. The rate of gall bladder emptying did not correlate with the rate of gastric emptying in any of the patients studied. These observations suggest that TV + P, but not HSV, causes considerable alteration in coordination of gall bladder and gastric emptying.