Familial Mediterranean fever is an autoinflammatory disorder characterized by recurrent fever and serositis. We aimed to describe serum vitamin B-12 and vitamin D levels and their correlation with self-reported sleep quality of pediatric FMF patients. Sixty-three children with FMF were enrolled to the study. Information on sleep quality was obtained using self-administration of Pittsburg Sleep Quality Index (PSQI). The patients were divided into subgroups depending on vitamin D serum concentrations: >= 20 and < 20 ng/ml. We also grouped patients according to their serum B-12 concentration: >= 200, < 200 pg/ml. B-12 levels were not correlated with PSQI scores, whereas significant correlation was found between vitamin D and total PSQI scores and daytime sleepiness. Total PSQI score, sleep disorders and daytime sleepiness sub-scores were statistically high in patients with serum D vitamin levels below 20 ng/ml. Sleep efficiency was found lower in patients with serum B-12 levels below 200 pg/ml. B-12 may have a positive role on effective sleep. More importantly, we suggest that vitamin D is protective against sleep disorders and poor sleep, it may also improve daytime activities.