A United Nations (UNHCR)-sponsored study has been undertaken, involving neurologists from the Turkish-speaking northern and Greek-speaking southern communities of Cyprus, to ascertain the prevalence of multiple sclerosis (MS) and to bring the medical personnel of the two communities to work together. The Turkish community includes both Turkish Cypriots and, since 1974, a big influx of immigrants from Turkey. The prevalence of MS among Turkish Cypriot men was significantly higher than in Turkish Cypriot women and was as high as has been found in men in recent studies in Northern Europe. It was also significantly higher than among Greek Cypriot men. The prevalence in Turkish Cypriot women was not significantly different to that found in Greek Cypriot women. Among the immigrants from mainland Turkey MS prevalence was significantly less for both men and women than among the Turkish Cypriots. In the Greek-speaking metropolitan area of Nicosia the prevalence of MS was 51 per 100,000, (males 43, females 59). The overall MS prevalence in four areas studied in Greek-speaking Cyprus, including three previously studied, was 42 per 100,000, (males 39, females 46 per 100,000).