Objective To evaluate the effect of blocking the posterior branc h of lumbar nerves in treatment of the lower lumbago and scelalgia caused by the i njury of the posterior branch of lumbar nerves. Methods 560 cases with lower lum bago and scelagia caused by the injury of the posterior branch of lumbar nerves were randomized into the treating group and the contrast group. Follow-ups were done 2 to 3 months after the treatment. Then the effects of the treatment were evaluated. Results The effective rate of the treating group was 98. 0 %,and th e excellect and good rate was 83.0 %; the effective rate of the contrast group was 83.3 %,and the excellect and good rate was 64.9 %. The differences in tre atment effects between the two groups are statistically significnt (P