In this study, we aimed to estimate serum 25-hydroxy vitamin D (25-OH-D) in Asian Indians and test for association between 25-OH-D levels, insulin resistance (IR) and metabolic syndrome (MS). Serum 25-OH-D was measured in a cross-sectional sample of 441 Indians, aged 39.7 ± 12.8 years (237 men and 204 women) with 27.9% prevalence of MS. Vitamin D insufficiency (12.5 to <50 nmol l(-1)) and hypovitaminosis D (50 to <100 nmol l(-1)) were present in 65.6 and 31.1% of participants, respectively. The 25-OH-D levels did not differ significantly between sexes (P=0.057). Multivariate regression analysis indicated a positive relationship between 25-OH-D and β-cell function (homeostasis model assessment (HOMA)-B; β=0.245, P=0.006), whereas regression coefficients for fasting glucose (β=0.262, P=0.794), insulin (β=-0.140, P=0.889) and HOMA-IR (β=-0.119, P=0.172) were insignificant. Sex-stratified analysis showed no linear trend for increasing quintiles of 25-OH-D with prevalence of MS or its components (P>0.05). Although highly prevalent, vitamin D insufficient status was not associated with MS or IR in Asian Indians of either sex.