Our aim was to assess the effect of dietary elimination of monosodium glutamate (MSG) and aspartame on perceived pain in fibromyalgia. A total of 72 female patients with fibromyalgia were randomized to discontinuation of dietary MSG and aspartame (n = 36) or waiting list (n = 36). Patients were requested to rate their pain using a seven-point scale. Comparisons between both groups showed no significant differences on pain referred during the baseline or after the elimination of dietary MSG and aspartame. The discontinuation of dietary MSG and aspartame did not improve the symptoms of fibromyalgia.