AIM: This paper reports a study to translate the English language version of the Quality of Life Index into Arabic and estimate its reliability and content validity. BACKGROUND: Quality of life has become an important concern in health care and social policy. It is a difficult construct to define and measure, as it is determined by cultural, ethical, personal and religious values. The generic Ferrans and Powers Quality of Life Index was developed to measure quality of life of healthy individuals. Specific versions of the index were developed for particular diseases, such as diabetes, cancer and end-stage kidney disease. The instruments were initially developed for English-speaking clients and were later translated into several languages and used within a variety of cultures. However, there were no Arabic versions of the tool available to measure the quality of life of general populations or of people with particular diseases. METHOD: The Quality of Life Index was translated into Arabic using two of the techniques suggested in the literature for translation - back translation and bilingual technique. The same process was followed in the translation of the original scale and various disease-specific versions of the instrument. The work took place between 1995 and 2004. FINDINGS: The translated Arabic Quality of Life Index demonstrated a high degree of accuracy of translation and estimates of content validity. Subsequent to the translation of the original scale into Arabic, 13 disease-related versions of the instrument were translated and are ready for use with clients who speak Arabic. Four of the versions have been used to collect data from clients. The results revealed high estimates of reliability for the generic, diabetes, cancer and dialysis versions. CONCLUSION: The Arabic version of the Quality of Life Index is highly reliable and has sufficient content validity for measuring quality of life of Arabic-speaking clients.