Τhe present study examines main psychometric properties of the World Health Organisation (WHO) quality of life (QoL) instrument, the WHOQOL-BREF with the inclusion of four national items. Participants were 425 adult native Greek speaking, grouped into patients with physical disorders, psychiatric disorders and healthy individuals. Participants were administered WHOQOL-BREF and 23 national items, the General Health Questionnaire (GHQ-28) and the Life Satisfaction Index (LSI). Confirmatory factor analysis produced acceptable fit values for the original model of 26 items within the four WHOQOL domains: physical health, psychological health, social relationships and environment. Testing for the fit of national items within this model, the results indicated four new items with the most satisfactory fit indices and were thus included forming a 30-items version. The national items refer to: (a) nutrition, (b) satisfaction with work (both loaded in the physical health domain), (c) home life and (d) social life (both loaded in the social relationships domain). Statistical tests were applied to the 26- and 30-items versions producing satisfactory results, with the 30-items version showing slightly better values. Furthermore, results on the 30-items version included: (a) internal consistency, which was found satisfactory, with alpha values ranging from α=0.67-0.81, while the inclusion of new items produced higher alpha values in physical health and social relationships domains, (b) construct validity with good item-domain correlations, as well as strong correlations between domain scores, (c) convergent validity, which was very satisfactory, showing good correlations with GHQ-28 and LSI, (d) discriminant validity, showing instrument's ability to detect QoL differences between healthy and unhealthy participants, and between physically ill and psychiatric patients, and (e) test-retest reliability, with ICC scores in excess of 0.80 obtaining for all domains. The WHOQOL-BREF Greek version was found to perform well with sick and healthy participants, demonstrating satisfactory psychometric properties. Use of the instrument may be recommended for clinical and general populations, for service or intervention evaluation, as well as for cross-cultural clinical trials.