Patterns of failure after treatment for carcinoma of the lung were analyzed by the major WHO cell types. Only diagnoses of the review panel of the Veterans Administration Lung Group were used. First sites of progression were analyzed for 185 patients in a clinical trial, and cause of death was evaluated in 300 consecutive autopsies from VALG studies. Clinical progression was similar for all cell types--20% failed locally and 30% developed metastases. Carcinomatosis or brain metastasis caused death in only 27% of patients with squamous, in over half with large cell and adenocarcinoma, and in 70% of patients with small cell carcinoma. Complications of the local tumor (infection, hemorrhage, and respiratory failure) caused death in 50% of patients with squamous, in 1/3 with large cell and adenocacrinoma, and in 21% of those with small cell carcinoma. These clinical and autopsy data suggest the need for aggressive treatment of the local tumor in all cell types, and systemic therapy for small cell carcinoma. Both local and systemic approaches are needed for large cell and adenocarcinoma.