This article discusses attempts to treat patients with subacute sclerosing panencephalitis with interferons. This method of treatment was applied over a span of about twenty years in one of three variants: (1) in seven patients natural interferon beta (Rentschler's Fiblaferon) was administered into the fluid space intralumbarly, (2) in seven patients naturalinterferon alpha (produced by the Institute of Hygiene in Helsinki) was administered intraventricularly by means of an epidurally implanted Rickham receptacle, and (3) in five patients recombined alpha 2b interferon was likewise administered intraventricularly by means of a Rickham receptacle. The best clinical outcomes were observed in group (2). No effects of the interferon treatment on immunological disorders were observed. Slight modifications of the bioelectrical activity of the brain were observed, however.