In light of the growing medical interest in the potential consequences of vitamin D deficiency, it is important that clinicians are informed about the varying factors that may complicate the assessment of vitamin D status and the diagnosis of deficiency. To better understand the frequency of vitamin D deficiency diagnoses in the ambulatory setting over time, the objective of this investigation was to examine unspecific, general, and bone-related vitamin D deficiency diagnoses between 2007 and 2010 and to determine whether the rate of diagnoses differed by patient age and sex. We used data from the National Ambulatory Medical Care Survey and the National Hospital Ambulatory Medical Care Survey to assess the rate of vitamin D deficiency diagnoses provided between 2007 and 2010 during outpatient visits with nonfederally employed physicians in offices and hospitals. Two hundred ninety-two unweighted patient visit records were included. Trends in vitamin D deficiency diagnosis over time, diagnosis of bone disease associated with a vitamin D deficiency diagnosis, and patient age and sex were reported. The number of diagnoses for vitamin D deficiency rapidly increased from 2007 to 2010. More than 97% of diagnoses were for unspecific vitamin D deficiency; 9.6% of vitamin D deficiency visits also resulted in a diagnosis of osteoporosis or bone fracture. Although the rate of diagnoses for vitamin D deficiency increased between 2007 and 2010, many diagnoses rendered were for nonspecific disease; therefore, vitamin D deficiency screening may have been ordered for preventive care purposes rather than as a diagnostic aid.