Objective To observe the clinical efficacy of tonifying kidney and fortifying Du meridian in treatingankylosing spondylitis. Methods Multi-center

randomized

double-blind

double dummy controlled method was adopted. One hundred and eighty four patients were enrolled

including 94 cases of kidney deficiency and Du meridian cold syndrome

and 90 cases of kidney deficiency and damp-heat syndrome. The patients with each syndrome were randomly divided into the treatment group and the control group. In the treatment groups

in addition to sulfasalazine simulation tablets

patients with kidney deficiency and Du meridian cold syndrome were given Bushen Qiangdu Quhan decoction（ 补肾强督祛寒汤）

and patients with kidney deficiency and damp-heat syndrome were given Bushen Qiangdu Qinghua decoction（ 补肾强督清化汤）. In the control groups

all the patients were treated with the sulfasalazine tablets and simulation Chinese medicine preparation. The treatment course was 12 weeks in each group. The clinical observation index（ overall score

spinal pain score

function index

spinal inflammation index

Chinese medicine syndrome score）

signs（ occiput to wall distance

mandible to sternum distance

finger to floor distance

thoracic expansion degree

spinal mobility

Schober’ s test）

erythrocyte sedimentation rate（ ESR）

and C-reactive protein（ CRP） in the two groups before and after treatment were compared. Chinese medicine clinical efficacy and the percentage of reaching the efficacy standard were determined. Results Totally 162 patients completed the trial. Among the patients with kidney deficiency and Du meridian cold syndrome

40 cases were in the treatment group

and 37 cases the control group. Among the patients with kidney deficiency and damp heat syndrome

42 cases were in the treatment group

and 43 cases in the control group. Patients with either syndrome in the treatment groups had superior Chinese clinical efficacy than those in the control group. After treatment

the clinical observation indexes and finger to floor distance

thoracic expansion degree

spinal mobility

Schober’s test and CRP in kidney deficiency and Du meridian cold syndrome treatment group were all better than those in the control group; the clinical observation indexes and the signs in kidney deficiency and damp heat syndrome treatment group improved significantly than those in the control group（ P < 0. 05 or P < 0. 01）

but there were no statistical difference in ESR and CRP between the groups（ P > 0. 05）. The percentages of reaching the efficacy standard in the treatment groups of each syndrome were also better than those in the same syndrome of the control groups（ P < 0. 01）. Conclusion Tonifying kidney and fortifying Du meridian could significantly improve the symptoms and signs of ankylosing spondylitis

with clear curative effect and good safety.