Objective: To determine the prevalence of vitamin D insufficiency and deficiency in the elderly patients with osteoporosis. Subjects and Methods: This prospective study consisted of 95 patients aged 60 years old or older, who were diagnosed with osteoporosis and treated in the Department of Rheumatology, Cho Ray Hospital during the period from June 2008 to March 2009.Results: 95 patients included 82 females (86.32%) and 13 males (13.68%).