Currently available interferon beta treatments require injections once to four times each week and patients with active disease might choose not to be treated because of concerns about the need for frequent injections. It is suggested that peginterferon beta-1a, with its less frequent dosing regimen, could address some of the factors that lead to avoidance of treatment or poor adherence, while still providing clinical benefits expected from approved interferon beta therapies. Only 1 year data have been presented so the long-term efficacy of peginterferon beta-1a is still not fully understood, and additional data from the completed 2-year study are awaited.