Background. The aim of the study was to determine the usefulness of selected anthropometric features in predicting the development of impairment of the strength of thumb & finger flexors after radical mastectomy. Material and methods. The analysis included 126 women who had undergone a radical operation for breast cancer. The strength of flexors of the fingers & thumb was evaluated before surgery and during 12-month follow-up. The results of muscle strength tests were referred to 15 anthropometric traits. Results. 23.8% of the women did not regain pre-surgery muscle strength, as attested by the results of all muscle strength measurements. There were statistically significant differences in mean body mass and the BM and Quetelet’s indices between women with persistent post-operative impairment of muscle strength and those who regained muscle strength following a radical mastectomy. Conclusions. Impairment of muscle strength below reference values in the finger & thumb flexors was seen in 23.8% of the mastectomy patients. Grasp strength decreases were most strongly correlated with body mass (correlation index 0.67). Post-operative weakening of the hand was significantly correlated with high body mass (>71.1 kg) and high values of the following indices: BMI (>29.8) and Quetelet’s index (>412).