Background. We examined the prognostic value of histologic indices in non-small cell lung cancer with particular interest in major blood vessel invasion. Methods. We studied 593 patients who had curative resection between November 1983 and December 1988. We determined the histology, T and N status, peritumoral lung tissue invasion, tumor stroma, necrosis, mitotic rate, and blood vessel invasion. Results. The median patient survival of the whole series was 3.2 years, with a 5-year survival of 38.9%. In univariate analysis, a high T stage, a high percentage of necrosis, blood vessel invasion, and N stage significantly worsened the survival. In multivariate analysis, only blood vessel invasion and, less significantly, T stage and lymph node metastasis remained independent prognostic factors. Conclusions. These results highlight the negative prognostic value of blood vessel invasion in non-small cell lung cancer and suggest that blood vessel invasion, T stage, and node metastasis are three unrelated and distinctive characteristics of resected non-small cell lung cancer.