A cohort of 137 patients with completely resected stage I or II adenocarcinoma of the lung was observed from the time of operation; the metastatic pattern determined at autopsy is described in relation to clinical, histologic, and laboratory variables. The pretreatment variables evaluated were performance status, age, gender, lactate dehydrogenase, stage, degree of differentiation, and histologic subtype of adenocarcinoma of the lung. Patients who survived longer than 30 days after operation were eligible for analysis, and 35 autopsies were performed in this patient group (autopsy rate: 39.8%). The most common intrathoracic metastatic sites were mediastinal lymph nodes (43%), lung (31%), pleura (20%), pericardium (9%), and heart (6%). The most common extrathoracic sites were liver (37%), brain (33%), bones (21%), adrenals (17%), and kidneys (17%). Patients undergoing resection for stage I disease had significantly fewer intrathoracic metastases than patients with stage II disease (p = 0.01). Patients who survived less than 1 year had significantly more extrathoracic metastases than patients who survived for a longer period (p = 0.01). Patients with highly differentiated tumors had fewer extrathoracic metastases than patients with less differentiated tumors. No other statistically significant differences were observed. Overall, patients with stage I adenocarcinoma of the lung had better local control of the disease at autopsy than those with stage II disease, but distant metastases are a large problem despite the favorable prognosis of this patient group. The extrathoracic metastatic potential was greatest for less differentiated tumors. An active adjuvant systemic therapy after resection is needed in selected patients with poorly differentiated adenocarcinomas of the lung, even in those with stage I disease.