Background: Muscle strength as an element of preparation and sport competition is one of the most important aspects in technical and tactical efficiency. The aim of this study was to define the level of relation between bioelectrical muscle activity and isokinetic strength parameters in 17–19-year-old judoists. Material/Methods: 30 judo athletes (17–19-year-old) took part in the research. The research was conducted in Gdańsk Academy of Physical Education and Sport Laboratory during 2006–2008. In the research authors used: to evaluate the isokinetic strength level, ”Concept 2 Dyno” device was used in the research, along with surface summary electrical bio-potentials reading on EMG AMT–8 CDN BORTEC BIOMEDICAL with ACQ software. Results: In the upper right limb there are more statistical significant correlations between isokinetic strength parameters and electrical muscle activities. In the lower limbs measurement of the left leg shows more significant correlations. Conclusions: Comparing the upper and lower limbs, it was noticed that the isokinetic strength parameters of the upper limbs are more correlated with the measured muscle electrical activities. Regarding the left and the right side comparison, the right side (the upper and the lower limb) isokinetic strength parameters are more correlated with the measured muscle activities.