Objective: To translate the WHO’s quality of life questionnaire, WHOQOL-100, into Persian language and assess the validity and reliability of this translated version.

Materials & Methods: To translate the questionnaire, a forward-backward procedure is used. A pilot sample of 60 university students was recruited to assess the repeatability and concurrent validity of the instrument. Then, 500 healthy and 500 disabled individuals were randomly selected using a multi-stage sampling technique. The internal consistency of the Persian version of the WHOQOL-100 was evaluated using the Cronbach’s alpha in this sample. In addition, a multiple linear regression model was utilized for assessing the discriminant validity of this instrument adjusting for different confounders.

Results: The test-retest analysis of the data from the pilot sample showed that the Persian version of the WHOQOL-100 has acceptable repeatability (ICCs for all six domains were more than 0.7). Also, computing the correlation between domains of WHOQOL-100 and WHOQOL-BREF showed satisfactory concurrent validity. Analyzing the data from 500 healthy and 500 disabled persons revealed that all the domains of WHOQOL-100 met the minimum level of acceptable internal consistency. The multiple regression results showed acceptable discriminant validity for all domains of this version of the WHOQOL-100, expect for the spiritual domain.

Conclusion: In general the Persian version of the WHOQOL-100 had satisfactory reliability and validity for assessing the quality of life in Iranian people. However, further research is recommended for challenging the problem of the spiritual domain.