BACKGROUND: There are no Colombian studies published that assess non-specific low back pain (NSLBP) risk factors in children. OBJECTIVE: To determine the factors associated with NSLBP in 73 children (19.2% girls) aged 10–12 years in one military school in Bucaramanga, Colombia. METHODS: A questionn aire was used to obtain information of risk factors. Subsequently, children's weight and height were measured. The backpack was weighed at the beginning of each day from Monday to Friday. Crude and adjusted prevalence ratios were calculated, with their respective 95% confidence interval (CI). RESULTS: The one-month prevalence of NSLBP was 39.7% (95% CI 28.4–51.9). In the multivariate analysis, carrying backpacks wearing between 12% and 20% of body weight, having a perception that the backpack is very heavy, and being a passive smoker increase the likelihood of NSLBP, while being 11-year-old compared to 10-year-old decreases the likelihood of having NSLBP, adjusted for gender, body mass index, and history of LBP in parents. CONCLUSIONS: High prevalence of low back pain was found in children between 10 and 12 years old. The study of the decisive factors of low back pain is important to identify children at risk, as well as to develop efficient primary prevention programs.