The present study examined patterns of cerebral activation during a working memory (WM) rehearsal task in individuals diagnosed with multiple sclerosis (MS) and in healthy adults. BOLD functional magnetic resonance imaging (fMRI) was performed using a 1.5 T GE scanner to assess activation during a WM task adapted from the Sternberg paradigm (Sternberg, 1969). Participants included 8 individuals diagnosed with MS, and 5 healthy controls (HCs) matched for age and education. Task difficulty was manipulated by increasing the length of time that strings of letters were to be rehearsed. Findings revealed increased right prefrontal cortex activation and increased right temporal lobe activation in individuals diagnosed with MS compared to HCs. The potential explanations for increased right hemisphere activation in persons with MS are discussed.