This study was conceived with the objective of assessing the correlation between ovarian reserve markers and vitamin D deficiency (VDD) in a selected group of Pakistani subfertile women presenting at a specialized subfertility treatment centre. The measurements of antral follicle count (AFC), serum anti-Müllerian hormone (AMH), serum follicle-stimulating hormone (FSH), and serum vitamin D (VD) levels were the main tools used for the assessment of ovarian reserve. Materials and methodsAll female patients aged 18 to 45 years presenting with primary and/or secondary subfertility at the Australian Concept Medical Centre in Karachi, Pakistan from August 2016 to July 2021 were included in the study. The data of all eligible patients were recorded in the pre-defined Performa designed for this study. The Kruskal-Wallis test was applied to report the distribution of the data. The correlation between the categorical variables (25-hydroxyvitamin D [25-OHD] levels with AFC and AMH) was assessed using the chi-square test and Spearman correlation. The comparison was based on vitamin D levels grouped into three categories: deficiency (<20 ng/ml), insufficiency (21-29 ng/ml), and sufficiency (>30 ng/ml). ResultsOne hundred ninety-nine cases were evaluated for AFC and hormone analysis. The mean age and BMI were 32.87±5.49 years and 28.27±4.97 kg/m 2 . VDD was noted in 127 (68.4%) cases. No significant difference was noted across BMI, age, duration of subfertility, AMH, and FSH across the VD categories. Moreover, a poor correlation was noted between VD, AMH and FSH on the scatter plot, between VD and FSH (r = −0.003, p = 0.966) and between VD and AMH (r = −0.068, p = 0.342), respectively. ConclusionsThis study showed a high frequency of VDD in Pakistani subfertile women, from a specialized subfertility center in the largest metropolis in the country. However, a statistically significant association was not found between the markers of ovarian reserve and VD, showing no ethnic differences in the native Pakistani population. Hence, VD supplementation is unlikely to have an impact on correcting the ovarian reserve status in subfertile women in Pakistan. However, this is a potential area of interest, and evaluation of other indices of reproduction/ovarian reserve and the effect of confounders is required to test this hypothesis longitudinally.