Objectives Vitamin D deficiency is a frequent health problem worldwide, especially as fewer people spend much time in the sun. Vitamin D deficiency is linked to several infectious and inflammatory conditions, including periodontal disease. However, its role in aggressive periodontitis (AgP) has not been well studied. We evaluated the association between vitamin D concentration and periodontal disease, both AgP and chronic (CP) periodontitis. Method and Materials Forty-seven AgP 55 CP and 27 control subjects participated. All patients were tested for serum vitamin D concentration (25(OH)D), parathyroid hormone, and serum bone-related biomarkers (alkaline phosphatases, calcium, and phosphorus) regulated by vitamin D. Results The patients with AgP had lower serum 25(OH)D concentration (11.22 +/- 4.8 ng/ml) than controls (16.9 +/- 6.4 ng/ml) and patients with CP (16.13 +/- 8.3 ng/ml; overall p value 0.0002). These associations remained significant after adjustment for age and gender (p = 0.002). No significant differences were observed in any bone-related biomarker among the three groups, and no association was observed with periodontal disease indices. Conclusions Our results suggest that vitamin D deficiency may be a potential risk factor for AgP. Given the high prevalence of vitamin D deficiency in AgP patients, routine screening for vitamin D status may be advisable in these subjects.