The paper is concerned with the description of clinical, x-ray and morphological investigation of 123 bronchoalveolar cancer patients. Three types of this disease were defined: nodular (homogeneous and nonhomogeneous), pneumonia-like (infiltrative and infiltrative-nodular) and mixed (focal-disseminated, focal-nodular and focal-infiltrative). These types of bronchoalveolar cancer are most probably stages of the same tumor process. Clinical and x-ray signs of each type showed correlation with a morphological picture of a tumor. Shadow nonhomogeneity as one of the main x-ray signs of bronchoalveolar cancer was shown to be determined by the "alveolar" structure of a tumor, a tendency to the formation of small cavities, filled with viscous mucosa and air. Correct clinical and x-ray diagnosis in all types of bronchoalveolar cancer (before the use of the morphological methods) was established in 45.5% of the patients.