Interest in leading prognostic determinants of proximal gastric adenocarcinoma (PGA) in comparison with distally located adenocarcinoma (DLA) of the stomach led to an analysis of data from 506 patients with PGA and 484 patients with DLA operated on between 1 April 1982 and 31 October 1984 and participating in a multicentre observational study to validate tumour node metastasis (TNM) stage groupings. The proportion of men with PGA was slightly higher than that of men with DLA (69 versus 63 per cent). Men more often had cardia carcinomas than women (14 versus 9 per cent); 74 per cent of these men but only 43 per cent of the women were less than 65 years old. Evaluation of data by a log-linear model indicated a strong partial association (P less than 0.001) between age and site; patients younger than 65 years more often had PGA than older patients. Advanced tumour stage and the intestinal type of carcinoma were more frequently seen in the elderly. More than twice as many patients with PGA in comparison with those with DLA (35 versus 15 per cent) had palliative surgery (moderate association, P less than 0.05). This may have resulted from different stages at different sites; advanced carcinomas (TNM stages IIIb and IV) were more often diagnosed in patients with PGA than in those with DLA (60 versus 38 per cent). Residual tumour left after surgery was associated with deeper infiltration (P less than 0.001). No difference between PGA and DLA groups with respect to histological type of carcinoma was established, but residual tumour was more frequently associated with a diffuse type carcinoma (P less than 0.01). An overall tendency to poorer long-term prognosis in PGA was seen for all TNM stages, with and without residual tumour, except for TNM stage II with residual tumour, even though patients with PGA were younger than those with DLA. These differences in long-term prognosis, however, are based primarily on poorer short-term survival for PGA, particularly for TNM stages Ib and II without residual tumour. A significant risk of surgical management, particularly for early-stage tumours situated in the upper part of the stomach, has therefore been recognized. Surgeons should appreciate the higher surgical mortality rate for patients with PGA when curative treatment requires more risky surgical techniques.