The HLA typing of 100 patients with multiple sclerosis (MS) and their differentiation according to the dynamics of the disease, the type of course and the degree of defect showed the following results: a significant increase in frequency of HLA B7 (P less than 0.05), independent of the severity of illness, a 4-fold increased frequency of the HLA haplotype A25, B18 with augmented occurrence in slight to moderate severity of the disability degree (P less than 0.05), less so in the dynamics of the disease, and only partially so in the relapsing-remittent course. These HLA constellations provide only a hint at the prognosis of MS; the findings could be an expression of the heterogeneity of the disease.