This study was performed to investigate the association between Lauren's histopathological classification system and different clinico-pathological characteristics in patients with gastric carcinoma. We revealed that the percentage of intestinal type tumour (ITT) increased with advancing age (52% in patients less than 60 years compared to 73% of octogenarians (P less than 0.001)). The male:female ratio was 1.7 for ITT versus 1.3 for diffuse type tumour (DTT (P = 0.12)). ITT was more common in proximally (fundus) localized tumours than in distal lesions (77% vs 65%; P less than 0.05). The proportion of patients with ITT decreased with advancing stages of the disease (70% in stage I and II vs 52% in stage IV (P less than 0.0001)). More patients with DTT had tumour infiltration in the resection margin (21% vs 9%; P less than 0.001). Intestinal metaplasia was found in 48% of those with ITT compared with 28% of those with DTT (P less than 0.001). No association was found between Lauren's classification and the ABO blood group or between the tumour types and infiltration in lymphatic or blood vessels. We conclude that gastric adenocarcinoma occurs in at least two different biological forms and that differentiation between the two is of relevance for treatment.