The aims of this study were to evaluate serum vitamin D levels in cases of recurrent otitis media and investigate the effect of vitamin D therapy on the risk of re-occurrence of the disease. This prospective study was performed by comparing serum vitamin D levels in children with recurrent otitis media and healthy children. Eighty-four children between 1 and 5 years of age and diagnosed with recurrent otitis media were enrolled as the study group. One hundred-and-eight healthy children with similar demographic characteristics were enrolled as the control group. Patients were divided into groups according to their serum 25(OH) vitamin D levels. In patients with low initial serum vitamin D levels, vitamin D therapy was administered in addition to conventional treatment for otitis media. Mean serum 25(OH) vitamin D level in the study group was 11.4 ± 9.8 ng/mL Serum 25(OH) vitamin D levels were below 20 ng/mL in 69 % (n = 58) of cases in this group. In the control group, mean serum 25(OH) vitamin D level was 29.2 ± 13.9 ng/mL and was below 20 ng/mL in 30 % (n = 32) of cases. Comparison of serum 25(OH) vitamin D levels and PTH in the study and control groups revealed a statistically significant difference (p < 0.05). Treatment was initiated in cases diagnosed with vitamin D deficiency, and patients were followed up in due course. The only episodes detected over the course of 1-year follow-up were one attack in five patients and two attacks in two. We believe that co-administration of supplementary vitamin D together with conventional treatments is appropriate in the management of upper respiratory infections such as otitis media.