This study aimed to examine the 12-month incidence and risk factors for the onset and persistence of low back pain (LBP) in undergraduate students. A 1-year prospective study was carried out among 684 healthy students in a large public university in Thailand. Data were collected using a self-administered questionnaire and a physical examination. Follow-up data were collected every 3 months. A total of 524 (77%) students were followed for 1 year. A total of 31% reported a new onset of LBP, of whom 31% reported persistent LBP. Having no low back support during computer work was a significant predictor for the onset and persistence of LBP. The onset of LBP was also associated with quadriceps muscle tightness. LBP is common among undergraduate students, and many of them may have persistent symptoms. Physical risk factor plays a significant role for the onset and persistence of LBP among the study population.