The aim of our study was to determine the prevalence of vitamin D deficiency (<20 ng/dl) among patients with fibromyalgia or muscle pain in a musculoskeletal clinic in the United Arab Emirates. Consecutive patients who were diagnosed with fibromyalgia and/or non-specific musculoskeletal pain (ICD-9 729.1) were screened for vitamin D deficiency. Patients were seen at follow-up after treatment with vitamin D was given. Improvement was assessed by a simple questionnaire. Patients (139) with muscle pain were seen in 2007. Average age was 40 +/- year; 95% were female; 69 (49%) were Arab, of whom 92% were veiled; 43 (30%) Indian of whom 11% were veiled; 23 (16%) were Caucasian; and four were East Asian (3%) and all wore western clothes. One hundred three (74%) of these patients had a low vitamin D level. Vitamin D deficiency was most common among Arab patients (86%) and Indo-Pakistani (87%) and least common among the Caucasians (8%) and was equally prevalent among veiled and non-veiled patients. Treatment resulted in clinical improvement in 90% of patients. Non-specific muscle pains among Arab and Indian-Pakistani populations may indicate vitamin D deficiency, and prompt treatment can result in resolution of symptoms.