High prevalence of low back pain (LBP) has been reported among farmers. A number of contributing factors have been associated with LBP. However, predictors for LBP in this population are unknown. This longitudinally designed study aimed to identify the predictors of LBP in a sample of rubber farmers whose work involves heavy manual labor. Three hundred and twenty-seven rubber farmers, aged 18 to 70 years who reported no LBP in the previous year, were face-to-face interviewed and examined physically. The incidence of LBP was assessed monthly. The 12-month incidence of LBP in the cohort was 35%. Having a history of LBP (hazard ratio = 1.55, 95% confidence interval = 1.05-2.30) and an active job (hazard ratio = 1.98, 95% confidence interval = 1.16-3.40) were the predictors for the new onset of LBP in this sample. These 2 factors could therefore potentially be targeted to prevent or reduce the incidence of LBP in rubber farmers.