This study was conducted to evaluate the prognostic significance of cyclin D1 and retinoblastoma (Rb) expression in combination with abnormal p53 accumulation in primary, resected non-small cell lung cancers (NSCLCs). We evaluated immunohistochemically the expression of cyclin D1 and Rb in 208 NSCLC patients whose resections were consecutively performed between January 1984 and December 1988 and determined their prognostic significance by comparison with follow-up data. Expression of cyclin D1 and Rb was detected immunohistochemically in 39 and 80% of the 208 NSCLCs, respectively. The Kaplan-Meier survival curve demonstrated that absence of cyclin D1 expression was significantly associated with shortened survival (P = 0.01 by the log-rank test), particularly in adenocarcinomas (n = 100; P = 0.004). Expression status of the Rb protein was not significantly associated with clinical outcome in any of the cohorts. The predictive power of these prognosticators was also assessed in combination with findings for abnormal p53 accumulation by multivariate analysis using the Cox proportional hazards modeling. Patients with cyclin D1-negative tumors had a significantly greater risk of earlier death than those with cyclin D1-positive tumors (risk ratio, 1.61; P = 0.03), particularly in adenocarcinomas (risk ratio, 2.49; P = 0.002). Cases showing abnormal p53 accumulation tended to have a shortened survival only when the tumors were adenocarcinomas (risk ratio, 1.75; P = 0.06). Absence of cyclin D1 expression may be a useful prognosticator for shortened survival in primary, resected NSCLCs with particular significance for adenocarcinomas. In contrast, Rb expression status is not a useful prognostic factor for any type of NSCLC.