A comparative analysis of zono - and tomography in 69 patients with minor peripheral cancer of the lung (26), tuberculoma (24), hamartoma (19) was performed. Zonography was shown to improve differential diagnosis between them. However, its importance is limited and helps to better visualize changes of the lung tissue around the formations, "a path" outgoing to the pulmonary radix and chest wall, and to detect the enlarged intrathoracic lymph nodes. Tomography is of greater informative value for the evaluation of the skialogical features of the formations and pleural changes. The combined use of zono - and tomography results in a better detection of different pathological lung formations of small sizes and changes in the pulmonary tissue enhancing the efficacy of differential radiodiagnosis between them.