Objectives: The aim of this study is to investigate the reliability and validity of Duruoz Hand Index (DHI) in patients with carpal tunnelsyndrome (CTS).Patients and methods: A total of 55 patients (50 females, 5 males; mean age 51.0±10.2 years: range, 30 to 73 years) aged ≥18 years who wereadmitted to the outpatient clinic of a rehabilitation hospital between December 2010 and December 2012 with the diagnosis of CTS bothclinically and electrophysiologically were included in this study. All patients completed DHI at baseline and repeated after a week interval.The Boston Questionnaire (BQ) and Health Assessment Questionnaire Disability Index (HAQ-DI) were filled out at baseline. And theinternal consistency reliability was tested using the Cronbach’s alpha. For the test-retest reliability, intraclass correlation coefficients (ICC)were calculated. The correlations between the DHI and both BQ and HAQ-DI were investigated for the construct validity.Results: Of the patients, 41 (74.5%) were housewives. Carpal tunnel syndrome was bilateral in 29 patients (52.7%). The Mean Body MassIndex was 31.2±5.5 kg/m2. The mean symptom duration was 22.8±23.7 months. The mean DHI scores for the first and second evaluationswere 23.25±20.64 and 20.45±20.07, respectively. The mean BQ symptom severity and functional status scores were 2.87±0.80 and 2.72±1.03,respectively. The mean HAQ-DI score was 0.91±0.66. The Cronbach’s alpha was 0.97 indicating excellent internal consistency reliability.There was a statistically significant correlation between the two measurements of DHI. The ICC value for total score was 0.88 indicating goodreliability. There was a statistically significantly positive correlation between the DHI and BQ (r=0.638, p<0.001). Also, DHI was significantlycorrelated with the HAQ-DI (0.613, p<0.001).Conclusion: Our study results suggest that DHI is a reliable and valid test which can be used for evaluating hand functions in CTS patients.