BackgroundVitamin D deficiency is a worldwide pandemic problem. With vitamin D having some role in exercise-induced inflammation, skeletal muscle mass and endurance, we studied its effect on functional outcome of athletes' post-Anterior Cruciate Ligament (ACL) reconstruction.MethodsA total of 153 patients who underwent primary ACL reconstruction were enrolled in the study. All patients were screened for vitamin D levels preoperatively. Patients were divided into 3 groups on basis of vitamin D levels; Group 1 patients had<20 ng/ml, group 2 patients 20-30 ng/ml and group 3>30 ng/ml. All patients were followed up for a minimum of 2 years.ResultsA total of 153 patients were enrolled in study. The average age of the patients was 24.122.12 years in group 1, 25.243.20 years in group 2 and 24.74 +/- 2.86 in group 3. The mean follow-up of patients was 2.8 +/- 1.2 years. At 2 years, the mean Lysholm score was 96.12, 96.49 and 97.0, respectively (p=0.75); mean WOMAC score was 3.33, 3.38 and 3.20, respectively (p=0.91); mean difference between the pre-injury and post-surgery Tegner level of sports activity at 2 years follow-up was 0.78, 0.78 and 0.85, respectively (P=0.51) and graft failure rate was 5.88%, 1.96% and 1.96%, respectively (p=0.43).ConclusionVitamin D has no effect on functional outcome and graft rupture rates in patients' post-primary ACL reconstruction.Level of evidenceProspective Cohort Study (Level III)