Three hundred and thirty consecutive cases of resected Stage Ia (TNM UICC classification) lung carcinomas were retrospectively reviewed with the aim of evaluating actuarial probabilities of recurrence within the 5th year from operation, according to the extent of resection, the cell type, and the T number. The probabilities of recurrence according to the pattern of failure were also assessed. Five-year overall probability of recurrence was 46.3%. Pneumonectomies showed a lower rate of relapse (37.4%) than lobectomies (49.2%), even though non significant. However, patients submitted to a lobectomy had a higher rate of 5-year survivors. Cell type had no significant impact on the probability of recurrence. 35.5% of patients with T1 carcinomas had evidence of relapse compared with 51.1% of patients with T2 tumors. This datum is explained by the presence in T1 group of a high share of squamous cell cases. Patients with T1 squamous cell carcinomas had, in fact, the best prognosis (26.5% recurred) among the subgroups obtained by stratification of T number and cell type together; loco-regional failure as exclusive modality of relapse had a 5-year rate of 19.7% and metastatic failure of 30.0%. Adenocarcinomas had a significantly higher impact on the occurrence of brain metastases.