Objectives: A relationship between low back pain (LBP) and poor postures has been previously established with a high prevalence observed in many occupations. This study aimed to investigate the prevalence of LBP, associated risk factors and impacts on farmers in South-West Nigeria. Materials and Methods: Six hundred and four farmers completed a 36-item closed-ended questionnaire which was translated to Yoruba language with content validity and back translation done afterwards. The questionnaire sought information on demographic data, 12-month prevalence, severity, history, causes and management of LBP, and its impacts on farm activities and the activities of daily living. Data was analyzed using the Statistical Package for Social Sciences (SPSS) version 17. Data was summarized using descriptive statistics of mean, range, frequency, standard deviation, percentage. Chi 2 and Mann-Whitney-U test were used to find association between variables. The level of significance was set at α = 0.05. Results: The 12-month prevalence of LBP among the respondents was 74.4%. Low back pain was described as moderate in 53.4%. Prolonged bending (51.3%) was the most related risk factor. A considerable proportion (65.9%) of the respondents were unable to continue some of the previously enjoyed activities. Males had significantly higher (p < 0.05) prevalence, recurrence and duration of LBP than the females. Conclusion: There is a high prevalence of LBP among farmers in South-West Nigeria. Age, sex and years of involvement in farming have a significant influence on the prevalence of LBP.