Factors of varying influence of excessive body weight on breast cancer (BC) development in reproductive and menopausal women are still to be fully understood. The present study was concerned with evaluation of lean body mass and body fat level (BFL) in 100 BC patients at clinical stage I-II. Fifty females were still cycling, while the rest had been in menopause for, at least, 12 months. Twenty eight females (including 24 of reproductive age) smoked, at least, 5 cigarettes a day. BFL in menopausal patients was significantly higher than in the reproductive group. However, the study established that (1) with body mass excess (Broca index) of more than 20%, as compared with the "normal" level, patients of reproductive age revealed an increase in both BLF and lean body mass, unlike menopausal patients; (2) this correlation was observed in non-smoking patients only. The results are discussed from the viewpoint of possible connections being between them and mechanisms of BC genesis and development.