Recent reports have suggested that the retention of blood group antigen expression on tumor cells may be an important prognostic factor for survival. From 1986 to 1991, 136 patients underwent operative resection for their T1 N0 non-small cell lung carcinoma. One hundred twenty tissue blocks were available for antigen testing, and the histologic types were as follows: adenocarcinoma (73 patients), squamous cell (39 patients), large cell/undifferentiated (7 patients), and mucoepidermoid (1 patient). Follow-up is complete for all patients (mean, 41 months). This distribution of patients among the blood groups was as follows: A, 56 (47%); O, 53 (44%); B, 9 (7.5%), and AB, 2 (1.7%). Immunostaining was performed for A, B, and H blood group antigens. The 5-year actuarial survival in the blood group A patients (53%) did not differ significantly from that in the blood group O patients (59%). Similarly, when tumors were examined for their respective antigens, no significant differences were found in the 5-year survival of either blood group A or O patients between the tumors that retain and those that lose blood group antigen expression. Retention or loss of blood groups A or O antigen expression does not predict survival in patients with early-stage lung carcinomas.