There has recently been a significant increase in the number of pub lications on and applications of bioelectric signals for diagnostic purposes. While the use of ECG (electrocardiography) is not surprising, the use of signals from registration of brain activity (EEG) and muscles activity (EMG) still finds new applications in various fields. The authors focus on the use of EMG signals for estimating hand grip force. Currently, EMG signals are broadly used in limb rehabilitati on after severe injuries, surgeries, long immobilizations. Such parameters as maximal voluntary contraction (MVC) used for that purpose do not enable comparison of the forces generated by the muscles, for example, of two different people. It is connected, inter alia, with individual features of the studied person, as well as with a significant scatter of the measured EMG values for the same muscle, e.g. on different days of EMG measurements. The paper presents results of preliminary research whose final e ffect is to develop a procedure allowing force estimation in force units and estimation of the accuracy of the results. A series of tests was performed on two people. The tests showed the most important elements influencing disturbance of homogeneity of the obtained measurements with the same stimulation of the muscle. The authors focus only on determining hand grip force.