To explore the psychometric properties of the Greek version of the World Health Organization Disability Assessment Schedule (WHODAS 2.0-12 item) in adult patients suffering from motor disabilities. The questionnaire of WHODAS 2.0-12 item was officially translated and cross-culturally adapted into Greek (WHODAS 2.0-12Gr). 136 adult patients with motor disabilities included in the present observational study. A reliability study was carried out to explore WHODAS 2.0-12Gr's internal consistency (Cronbach's a), repeatability (Pearson's r) and test retest test-retest reliability between the WHODAS 2.0-12Gr outcomes of day-1 and day-8 [intra-class correlation coefficients with 95% confidence intervals (ICC 95%CI)], and the convergent validity (item-total correlation) of the questionnaire. Exploratory factor analysis (EFA) was used to explore the construct validity of the WHODAS 2.0-12Gr, while the concurrent validity of the questionnaire was testing against the Greek Medical Outcomes Study 36-item Short Form Health Survey version 1.0 (SF-36v1.0-Gr). Reliability properties: WHODAS 2.0-12Gr Cronbach's a was 0.814 (p < 0.001), Pearson's r value was 0.980 (p < 0.001) and ICC (95%CI) was 0.990 (0.985-0.993) (p < 0.001). Validity properties: Pearson's r values of item-total correlation were ranged from 0.376 to 0.736. EFA extracted a 3-factor model. Regarding concurrent validity, the significant correlations between the WHODAS 2.0-12Gr and the SF36v1.0-Gr ranged from -0.169 to -0.720. WHODAS 2.0-12Gr showed significant high to excellent reliability and significant weak to strong validity properties. Overall, it can be suggested that WHODAS 2.0-12Gr could be a reliable and valid tool for assessing patients with motor disabilities.