Studies of histocompatibility antigens in 25 patients, Russians by nationality, suffering from multiple sclerosis showed that antigens HLA-B7 were found in them more frequently than in healthy subjects. Also prevalence of antigens A2 and A3 was noted in the patients, each antigen being prevalent depending on the process type. Antigen A2 was prevailing in patients with a relatively benign process, while antigen A3 was predominant in patients with a rapidly progressing disease that led to grave affections of the nervous system.