Objective To evaluate the therapeutic effect of Tongyang Jiedu Decoction（Decoction for circulating yang and toxic substances） in treating nodular-cystic acne.Methods The 87 patients with nodular-cystic acne in TCM syndrome of yang stagnation and cold obstruction were randomized into 2 groups.The 44 in the treatment group were treated with Tongyang Jiedu Decoction for oral taking

one dose per day

taken in the morning and in the evening respectively

and the 43 in the control group were treated with Dahuang Zhechong Pills [Pills of Dahuang（Radix et Rhizoma Rhei） and Zhechong（Eupolyphaga seu Steleophaga）] for oral taking

3g each time

twice daily.Treatment course was of 8 weeks.The scores of skin lesions and TCM symptoms in both groups before and after treatment were compared respectively and the untoward reactions were observed.Results The total effective rate of the treatment group and the control groupwas 86.4%

and 65.1% respectively.The effect of the treatment group was superior to the control group（P<0.05）.The total score in both groups was lowered from the 2nd week on after treatment.In the in-group comparison with before treatment

the total score of 8 weeks after treatment was significantly different as compared with those of the 2nd week

the 4th week

and the 6th week（P<0.01）.From the 4th week on

the total score in the treatment group was significantly different with that in the control group at the same time（P<0.05 or P<0.01）.The improvement of the treatment group in the decreasing rate of total score and symptom score from the 2nd week on was superior to those of the control group

and the difference was significant（P<0.01）.There was no significant difference in the decreasing rate of skin lesion score and the incidence of adverse events between the two groups（P>0.05）.Conclusion Tongyang Jiedu Decoction is effective in treating nodular-cystic acne in the syndrome of yang stagnation and cold obstruction.