One hundred and eighteen primary breast cancer (BC) patients, 35 of whom were smokers, in clinical stages I-II of the disease were examined. In order to investigate whether smoking changes endocrine function in BC patients, some indices of the hormone-metabolic status of smoking and non-smoking patients of reproductive and menopausal age were compared. It was found that in smokers with BC there was a decline in body weight and body fat content, a lack of lean body mass accumulation along with body mass increase, a tendency to hypotriglyceridemia and hypoinsulinemia, accelerated development of the upper type of body fat distribution with ageing, intensified gonadotropin secretion, shifts in steroidogenesis and SHBG level and elevated catecholamine execretion. It is suggested that a possible relation between hormone-mediated effects inherent to smoking and the mechanisms promoting genotoxic type of hormonal carcinogenesis and the factors of breast cancer prognosis cannot be excluded.