Objectives:Lao Juan(LJ,劳倦) is a syndrome described in Chinese medicine(CM) that manifests with fatigue,fever,spontaneous sweating,indigestion,work-induced pain,weakness of the limbs,and shortness of breath.The present study was conducted to examine the reliability and validity of a Lao Juan Questionnaire(LJQ).Methods:A total of 151 outpatients and 73 normal subjects were asked to complete the LJQ.Seventy-tiiree normal subjects were additionally asked to complete the Chalder Fatigue Scale(CFS).Twelve clinicians determined whether the151 outpatients exhibited LJ or not.The internal consistency and construct validity for the LJQ were estimated using data from the outpatient subjects.The CFS data were used to examine the concurrent validity of the LJQ.Total LJQ scores and the clinicians’ diagnoses of the outpatients were used to perform receiver operating characteristics(ROC)curve analyses and to define an optimum cut-off score for the LJQ.Results:The 19-item LJQ had satisfactory internal consistency(α=0.828) and concurrent validity,with significant correlations between the UQ and the CFS subscales.In the test of construct validity using principal component analysis,a total of six factors were extracted,and the overall variance explained by all factors was 59.5%.In ROC curve analyses,the sensitivity,specificity,and area under the curve were 76.0%,59.2%,and 0.709,respectively.The optimum cut-off score was defined as six points.Conclusions:Our results suggest that the LJQ is a reliable and valid instrument for evaluating LJ. Objectives: Lao Juan (LJ, 劳 倦) is a syndrome described in Chinese medicine (CM) that manifests with fatigue, fever, spontaneous sweating, indigestion, work-induced pain, weakness of the limbs, and shortness of breath. The present study was conducted to examine the reliability and validity of a Lao Juan Questionnaire (LJQ). Methods: A total of 151 outpatients and 73 normal subjects were asked to complete the LJQ. Seventy-tiiree normal subjects were further asked to complete the Chalder Fatigue Scale (CFS Twelve clinicians determined whether the internal consistency and construct validity for the LJQ were estimated using data from the outpatient subjects. The CFS data were used to examine the concurrent validity of the LJQ. Total LJQ scores and the clinicians’ diagnoses of the outpatients were used to perform receiver operating characteristics (ROC) curve analyzes and define an optimum cut-off score for the LJQ. Results: The 19-item LJQ had satisfactory inter nal consistency (α = 0.828) and concurrent validity, with significant correlations between the UQ and the CFS subscales. the test of construct validity using principal component analysis, a total of six factors were extracted, and the overall variance explained by all factors was 59.5%. In ROC curve analyzes, the sensitivity, specificity, and area under the curve were 76.0%, 59.2%, and 0.709, respectively. The optimum cut-off score was defined as six points. Conclusions: Our results suggest that the LJQ is a reliable and valid instrument for evaluating LJ.