The objectives of the current study are to 1) compare the mean RBC omega-3 content in female fibromyalgia patients compared to that of healthy controls and female SLE patients, and to 2) assess the correlation between RBC omega-3 content and between the severity of physical (e.g. pain) and mental (e.g. depression) in fibromyalgia and Systemic Lupus Erythematosus (SLE).