Accidental low back pain at the workplace was classified into two groups; 177 cases of the organic type and 176 cases of the non-specific type. Concerning the recuperation period, the length of leave, and the amount of compensation for recuperation, medical cost and leave of absence, a comparison was made between two groups. Regarding age, sex, and the type of work, no difference was found between the organic and the non-specific groups. However, the non-specific group showed lower values than the organic one for the duration of recuperation and leave and the amount of compensation for medical cost and leave of absence. Multiple regression analysis showed that the difference in the type of low back pain had more influence on the duration and cost than that in sex and age. The prognosis of non-specific low back pain is better than that of organic one in terms of cost and duration.