We report on nine patients with multiple sclerosis who had received interferon beta-1a treatment for 6 months or more. Seven patients were Chinese and two were Caucasian. Seven patients had the relapsing-remitting type of multiple sclerosis, one had the primary-progressive type, and one had the progressive-relapsing type. Among the six compliant patients with the relapsing-remitting type of disease, four had less frequent relapses after treatment. This study could not show whether or not the use of interferon beta-1a was beneficial to non-compliant patients, or patients with other types of multiple sclerosis.