Multiple sclerosis is a chronic disease characterized by demyelination and neurodegeneration of the central nervous system. Immunomodulatory treatment is possible at an early stage of the disease, and consists of injections of either beta-interferon or glatiramer acetate. The drugs are not curative, and the need for frequent injections may give rise to a serious problem regarding adherence to treatment. The present study analyzed the database of all Brazilian patients using glatiramer acetate between June 2003 and December 2006 who had enrolled in the patient program run by the pharmaceutical company commercializing the drug. The rate of treatment discontinuation was 10% over this period, and the main reason for suspending the drug was medical decisions (47% of all discontinuations), rather than side effects or the patient's choice. The present work did not take into consideration the regularity of injections and the main objective was to assess discontinuation. It was concluded that adequate healthcare, education, and a specifi c program for patients were the factors responsible for this 90% adherence to glatiramer acetate treatment in Brazil.