It is still widely accepted that evaluation of estrogen and progesterone receptors (ER, PR) in breast cancer tissue is one of the basic predictive indicators of hormonal therapy success. Evaluation of hormonal receptors is usually done once at the time of biopsy or surgery on the breast regardless of the effect of time. In a retrospective evaluation of 1301 medical records of breast cancer patients the authors wanted to identify any time period dependence in quantitative or qualitative hormonal status. Steroid receptors were measured in breast cancer tissues by cytosol-based ligand-binding technique. The results suggest a strong time period dependence in hormonal status. In premenopausal patients simultaneous evaluation of ER/PR revealed an increased frequency of both positive receptors in the autumn months, and a decrease in the spring months. In postmenopausal patients, both positive receptors were found more likely in the summer months and both negative in the late winter months. Our results suggest that one evaluation of hormonal receptor status does not necessarily provide an accurate estimate of the hormonal status in breast cancer patients.