OBJECTIVE: To investigate the effects of a replacement diet with Khorasan wheat products in patients with fibromyalgia, in comparison with a similar replacement diet with control products made from organic semi-whole-grain modern wheat. DESIGN: Randomized, double-blinded crossover trial. SETTING: Outpatient clinic. SUBJECTS: Twenty subjects (19 female and one male, mean age = 48.9 ± 12.3 years) with fibromyalgia. METHODS: Participants were randomly assigned to consume either Khorasan or control wheat products (pasta, bread, crackers, biscuits) for eight weeks and then crossed. Validated self-administered questionnaires were collected from each subject at the beginning and end of each intervention period. RESULTS: A general linear model for repeated measurement, adjusted for potential confounders, showed that the overall score reported from each questionnaire improved after both intervention and control periods, but the effect was more evident after the intervention with Khorasan. In particular, a statistically significant difference in Widespread Pain Index (WPI) + Severity Scale (SS) and Functional Outcome of Sleep Questionnaire (FOSQ) was observed, which decreased significantly by 21.5% and 11.7% respectively, only after the Khorasan period, while no statistically significant variations were reported after the control period. Similarly, FM Impact Questionnaire scores decreased significantly only after the Khorasan period, with a reduction that was significantly different between the intervention and control periods (-22.5% vs -0.3%, P = 0.037). The improvement was even greater in people with higher symptom severity. CONCLUSIONS: A dietary intervention with Khorasan wheat products seems to benefit patients with fibromyalgia, especially those with greater symptom severity.