The aim of the study was to reveal correlation of dental morphology and bioelectric activity of masticatory muscles. The study included 76 young adults (47.4% females and 52.6% males) divided in 3 groups according to dental morphology features: intact teeth (26 patients), dental decay in fissures with intact cusps (25 patients), pronounced dental decay with varying degree of crown destruction (25 patients). Electromyography (EMG) was used to document the bioelectric activity (BEA) of temporal and masticatory muscles. The study showed high level of correlation of destructive teeth changes with BEA of masticatory muscles. Intragroup correlation proved direct link of BEA to the number of decayed teeth. EMG activity differed significantly between groups 2 and 3. There was no statistically significant difference between groups 3 and 1 mostly because of high variability of BEA in group 3. Relative activity of temporal and masticatory muscles increased in groups 2 and 3 by 2 and 4% and 38 and 19%, correspondingly. There was no significant impact of gender or emotional status on masticatory muscles BEA.