Immunomodulatory treatments for relapsing-remitting multiple sclerosis (RRMS) are not efficacious or tolerated in all patients. It is important to evaluate alternative classes of treatment in patients failing first-line therapy. The objective of this prospective observational study was to evaluate the efficacy and safety of glatiramer acetate in patients, to whom beta-interferons could not be administered. The study included patients with RRMS who were intolerant to or had contraindications to beta-interferon. After initiation of glatiramer acetate treatment, follow-up visits were made every 3 months, when data on neurologist-ascertained relapses and disability [Expanded Disability Status Scale (EDSS) score] were collected. Tolerability was evaluated by spontaneous adverse event reporting. Overall, 205 patients were studied and 113 (55.1%) treated for at least 4 years. The proportion of patients presenting over three relapses per year decreased from 51.2% to 8.4% in the 2 years following treatment initiation. Over 5 years of treatment, mean annualized relapse rates and mean EDSS scores remained stable (0.4-0.6 relapses/year and 3.6 +/- 1.8-3.3 +/- 2.1 respectively). Adverse events were reported by 179 patients, leading to discontinuation of treatment in 10 patients. Patients with RRMS to whom beta-interferons cannot be prescribed can benefit from treatment with glatiramer acetate.