- OBJECTIVES: The objectives of this systematic review and meta-analyses are (1) to estimate the prevalence of hypovitaminosis D in fracture patients and (2) to summarize the available evidence on the efficacy of vitamin D supplementation in fracture patients. DATA SOURCES: A comprehensive search of the MEDLINE, Embase, PubMed, and Cochrane Central Register of Controlled Trials databases was conducted. Conference abstracts from relevant meetings were also searched. STUDY SELECTION: We included studies that investigate vitamin D insufficiency or examine the effect of vitamin D supplementation on 25-hydroxy-vitamin D (25(OH)D) serum levels in fracture patients. DATA EXTRACTION: Two authors independently extracted data using a predesigned form. DATA SYNTHESIS: We performed a pooled analysis to determine the prevalence of postfracture hypovitaminosis D and mean postfracture 25(OH)D levels. We present detailed summaries of each of the studies evaluating the impact of vitamin D supplementation. RESULTS: The weighted pooled prevalence of hypovitaminosis D was 70.0% (95% confidence interval: 63.7%-76.0%, I = 97.7). The mean postfracture serum 25(OH)D was 19.5 ng/mL. The studies that evaluated the efficacy of vitamin D supplementation suggest that vitamin D supplementation safely increases serum 25(OH)D levels. Only 1 meeting abstract showed a trend toward reduced risk of nonunion after a single large loading dose of vitamin D. CONCLUSIONS: This review found a high prevalence of hypovitaminosis D in fracture patients and that vitamin D supplementation at a range of doses safely increases 25(OH)D serum levels. To date, only 1 pilot study published as a meeting abstract has demonstrated a trend toward improved fracture healing with vitamin D supplementation. LEVEL OF EVIDENCE: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.