Thirty bronchiolar carcinomas were studied, and were compared with pulmonary adenocarcinomas. Differentiation is difficult, as there is great overlap of morphological patterns. Bronchiolar carcinomas may arise from bronchioles or from atypical metaplasia adjacent to lung scars. Over half were associated with preexistent scarring. Bronchiolar carcinomas are usually peripheral, frequently asymptomatic, and most often present on x‐ray as a solitary nodule. Multiple nodules, usually due to aerogenous metastasis, were present in 57% on histologic examination. Resection rate was 80%, but only 14% of total patients were 5‐year cures. We conclude that there is neither morphological, histogenetic, nor clinical reasons for separating bronchiolar carcinoma from adenocarcinoma of the lung, and recommend that the term “bronchiolar carcinoma” be discarded.