Introduction: Although several observationalstudies have investigated the association between vitaminD status and schizophrenia, we are aware of no comprehensive meta-analysis in this regard. Objective: We aimed to conduct a systematicreview and a meta-analysis of observationalstudies to summarize the available data on the association between serumvitaminDlevels and schizophrenia. Methods: A systematic research on all published articles until October 2013 was conducted in PubMed, ISI (Web of science), SCOPUS, and Google Scholar. All observationalstudies that had measured serumvitaminDlevels in schizophrenic patients were included in the systematicreview. After considering exclusion criteria, we had 19 studies for the systematicreview that were included in three separate meta-analyses: 1) a meta-analysis on mean levels of 25-hydroxyvitamin D [25(OH)D] (n = 13); 2) a meta-analysis on the prevalence of vitaminD deficiency (n = 8); 3) a meta-analysis on odds ratios (n = 8). Results: Findings from a meta-analysis on means revealed that the overall mean difference in serum 25(OH)Dlevels between schizophrenic patients and control participants was -5.91 ng/mL [95% confidence interval (CI) -10.68, -1.14]. Subgroup analyses based on study design, the patient's hospitalization status, study quality, and study location did not explain between-study heterogeneity; however, type of biomarker assessed [25-dihydroxyvitamin D3 vs 25OH)D)] could account for some degree of heterogeneity. Results from the meta-analysis on the prevalence of vitaminD deficiency indicated that the overall prevalence of vitaminD deficiency in schizophrenic patients was 65.3% (95% CI 46.4%-84.2%). Findings from the meta-analysis on odds ratios indicated that vitaminD-deficient persons were 2.16 times (95% CI 1.32, 3.56) more likely to have schizophrenia than those with vitaminD sufficiency. No evidence of heterogeneity was detected. Conclusion: We found a strong association between vitaminD deficiency and schizophrenia. However, randomized clinical trials are required to confirm our findings.