From 351 transthoracic punctures with a fine needle, the authors determine their method of exam. The cytologic study of the samples permits a positive diagnosis of pulmonary opacity for 60 p. cent to 70 p. cent of the cases. The rentability reaches 89 p. cent for malignant lesions. The complications with the fine needle are very unusual comparatively to the technics allowing a histologic study, although rentability is equal for these two methods.