An epidemiological investigation of 878 workers(male 812, female 66) who suffered from low back injury(LBI) in some workplace of Pusan city from January 1 to December 31 in 1992 was carried out to obtain the various informations of the prevention and management in the occupational low back pain(LBP). The results were summarized as follows: 1. The mean age of LBP workers was 39.3±10.4(18-67) in male 48.5±12.6(21-69) in female workers. And the most common age groups were the 4th decade in male and the 6th decade in female workers. 2. In the frequency distribution of LBI according to the kind of industry, manufacturing industry was most frequent, and industry of construction, transport-storage-communication were the next in order. Among manufacturing industry, LBI of metallic products and machinery was the most frequent. 3. The occupational frequency of LBP was technical worker, monotonous worker, driver of automobile, driver of heavy equipment and office worker in order. 4. The cumulative percentage of LBI was 6.9% at the first day of employment and 90.8% until 10 years after employment. 5. The mean working duration from employment to onset of injury was 1081 days(about 2.9 years) and the working duration according to occupation was the shortest in driver of heavy equipment(502 days) and longest in office worker(1982 days). 6. The careless handling of object was the most common cause of LBI, and fall down, slip down, collision and traffic accidents were the next in order. 7. The most common cause of LBI according to occupation was traffic accident in driver of automobile, fall down in driver of heavy equipment and careless handling of object in office worker respectively. 8. The case of localized LBI were 517(58.9%) and the cases of LBI combined with other injuries, such as head, neck, trunk, arm or leg, were 361(41.1%) 9. Lumbar sprain was the most frequent diagnosis of LBI, and Herniated Nucleus Pulposus(HNP) and lumbar fracture were the next in order. 10. In multiple injuries, LBI combined with multiple body injury was the most frequent, and the next was LBI combined with arm and leg, with trunk, with head and with neck in order. 11. LBI combined with multiple body injury was the main injury in fall down, slip down and traffic accident, and lumbar sprain was the main injury in careless handling of object.