Between December 1972 and March 1974, clinical, thermographic and mammographic breast examinations were carried out on 4005 patients. In 546 patients palpable breast tumors were found, of which 456 were clarified by the conventional surgicalhistological procedure, 105 cases of carcinoma being found. In 128 of the 4005 patients (=3.2%), 184 cysts were found. Of the 128 patients with breast cysts, an operation had to be performed on 3 because of the pneumo-cystographic findings, on 5 because of doubtful cytological findings, and on 30 because of an additional solid lump (which included 1 carcinoma and 1 carcinoma in situ). Of all patients examined during that period for palpable breast tumors, 90 (=16.5%) were spared a breast operation thanks to fine-needle aspirations confirming the presence of harmless cysts only. The proportion of relapses after one aspiration of the cyst, a procedure which can be repeated at any time, was 15.7% in this sample.