Despite years of extensive research, the physiological role of recurrent inhibition (RI) is still far from being clear. We decided to study RI between human motoneurons (MNs) during isometric constant force contractions, which has never been systematically analyzed before. The paper presents a description of a system for detection of RI. In the system several methods for analysis of correlations between single motor units (MUs) were implemented. The software was developed in environment DELPHI 6. The results of evaluation of the system on the basis of the data obtained in the computer simulations are presented. The system detects recurrent IPSPs of amplitudes as low as 50 /mi V.