Objective To evaluate the clinical efficacy of Liuwei Dihuang Capsule（ 六味地黄胶囊） in the treatment of liver-kidney yin deficiency syndrome in N of 1

randomized controlled

double-blinded trial and to evaluate the applicability and reliability of this method in the evaluation of syndrome response. Methods The observation period and the elution period of Liuwei Dihuang Capsule were determined by pre-test. The N of 1 randomized controlled double-blind test method was used to conduct two rounds of trials in the same individual. A total of 24 subjects participated in the trial and took the patients’ clinical symptoms as their most concern as efficacy evaluation indicators. Data were processed using the t-test

repeated measures analysis of variance

and single case meta-analysis to assess the reliability of the results. Results Among the 19 subjects who completed the clinical trial

5 subjects met the effective criteria

10 subjects met the possible effective criteria

and 4 subjects were ineffective. The t test

repeated measures analysis of variance

and meta-analysis were used to extrapolate the trial results. Three statistical analysis methods confirmed that Liuwei Dihuang Capsule can reduce clinical symptom scores（ P < 0. 01） compared with placebo. Conclusion N of 1 randomized controlled trials can be used to evaluate the therapeutic effect of syndrome-like Chinese medicines

and they are applicable and reliable.