The Health of the Nation Outcome Scales for Children and Adolescents (HoNOSCA) is a brief measure of outcomes. Evidence for the effectiveness of patient treatments conducted in mental health services is limited in Greece. Thus, in an attempt to employ an easily administered and valid outcome measure, to assess outcomes in clinical practice for children and adolescents, but also to be able to compare the results across countries, the HoNOSCA was the measure of choice. In this study we have translated and validated it in a Greek sample. We have investigated the inter-rater reliability, intraclass correlation, concurrent validity, and clinical change across time, of the HoNOSCA Greek translation. The results show that the Greek translation of HoNOSCA is a reliable and valid instrument. It can be used for clinical, managerial, research and audit purposes, but, most importantly, to facilitate multinational clinical research and comparison of data with other countries.