Even in advanced tumors of the breast, it may be interesting to know the steroid receptor status (RS) for therapeutic and prognostic purposes. When, for clinical reasons, surgical biopsy is not advisable, a morphologic technique may be attempted on cytological material. In the past few years, we have employed the cytochemical method described by Lee (RSf) on cytological material obtained from 31 primary and 34 secondary tumors; adequate material and follow-up were available in 42 cases. Patients with positive results (strong and diffuse fluorescence of neoplastic cells) usually had better prognosis and longer disease-free interval and total duration of disease. The majority of patients responded to endocrine manipulation. In contrast, weak positivity or negative results were associated with a poorer prognosis. If these results are confirmed in larger series of cases and for longer periods of observation, the morphological evaluation of RS on cytological material could significantly contribute to the management of breast cancer patients.