In this paper, the authors present a description of the clinical and psychological data of three girls with ring chromosome 15. These children were carefully observed and tested on their mental level and school skills, and the results are compared with the findings in the literature. In general, patients with ring 15 present a mild to moderate mental retardation, with some language difficulties at early age. Observation of behaviour and social skills, present these patients as cordial, willing and with good social integration, despite their severe growth failure.