Background: One of the most common musculoskeletal conditions that impair quality of life and cause functional impairment is chronic mechanical low back pain (CMLBP). Objective: The purpose of this study was to assess the gastrocnemius electro-myographic activity when compared to healthy controls in patients with CMLBP. Patients and Methods: Fifty-two male and female participants were invited to participate in this study, divided as the following: group (A) (Study group) involved 26 participants with chronic mechanical low back pain, and group (B) (Control group) involved 26 age-matched healthy volunteers.Results: There were no significant differences between study group (A) and control group (B) in the electro-myographic activity of gastrocnemius muscle (amplitude and frequency). In addition, there were no significant correlations between gastrocnemius muscle activity and pain intensity measured via visual analogue scale (VAS), static balance measured via single leg stance test and dynamic balance measured via Y balance test. Conclusion: Electro-myographic activity of gastrocnemius muscle seems to be not affected in chronic mechanical low back pain patients.