Purpose: This study was done to examine physical, psycho-social, and individual factors influencing musculoskeletal symptoms among Korean military trainees. Methods: Using a correlation study design, military trainees who had completed almost of all the basic combat training (BCT) days were recruited from two military training units selected by convenience sampling. Data from 415 participants were analyzed. Results: Prevalence of musculoskeletal symptoms was 29.6% defined as a participant having pain or discomfort in one or more body parts during training hours for more than seven consecutive days. Back/pelvic (10.8%), knees (10.1%), shoulders (7.7%), feet/toes (5.6%), ankles (4.8%) were prone to musculoskeletal symptoms. Musculoskeletal symptoms appeared to be related to physical exertion during BCT, stress during BCT, social support from fellow trainees, or previous musculoskeletal injuries. In the logistic regression model, physical exertion during BCT (OR=2.27, 95% CI: 1.42~3.65), stress during BCT (OR=1.79, 95% CI: 1.15~2.78), and previous musculoskeletal injuries (OR=1.58, 95% CI: 1.01~2.47) were the significant factors affecting prevalence of musculoskeletal symptoms. Conclusion: Findings indicate that physical exertion and psycho-social stress should be managed to prevent musculoskeletal symptoms in military trainees with more attention being given to trainees having a history of musculoskeletal injuries.