ABSTRACT: Most multiple sclerosis (MS) therapies are injectable drugs, and the frequency of injections has been shown to be inversely proportional to overall compliance. One method of improving therapeutic compliance and thus clinical outcomes is to develop medications that require less frequent dosing. One of the most promising modification techniques to extend the bioavailability of a drug is poly(ethylene glycol) conjugation (pegylation), which increases the size of a molecule by attaching polyethylene glycol moieties to the parent compound, resulting in slower clearance and metabolism. This approach has been used to improve the efficacy of a number of therapeutic molecules, including interferons. Peginterferon beta-1a, a pegylated form of interferon beta-1a, is currently in phase III clinical trials for relapsing MS and has the potential to improve patient compliance by reducing the number of injections while maintaining clinical efficacy. The role of nurses in educating patients about the effective use of this new MS therapy is discussed.