Abstract Background: the prevalence of subclinical hypothyroidism worldwide is commoner than the overt disease. Limited studies discussed the vitamin D levels in subclinical hypothyroid patients. Giving vitamin D supplements may prevent form developing overt hypothyroidism. In this cross-sectional case-control study, we described the differences in the vitamin D of adult Saudis with and without subclinical hypothyroid dysfunction. Methods: This is an observational single-center, retrospective, age, and sex matched, case-control study. A total of 60 subjects [41 healthy controls, 19 subclinical hypothyroid case] were included. 25(OH) vitamin D, TSH, free T4 and free T3 are measured in both groups. Results: Subjects with subclinical hypothyroid dysfunction had a significantly lower serum Vitamin D than controls (p value 0.016) although both groups fall below vitamin D sufficiency levels. Correlation is found between both vitamin D and TSH, p value 0.036. but it was found to be less statistically significant positive relation, r value is 0.279, (R square = .078, beta regression coefficient = -.055 and p value