The objectives were to determine the effect of macronutrient modification on vitamin D status and if change in 25-hydroxy-vitamin D concentration influences components of metabolic syndrome in obese African American girls. Methods. Five-week intervention using reduced CHO (43 carbohydrate; 27 fat: SPEC) versus standard CHO (55 carbohydrate; 40 fat: STAN) eucaloric diet. Subjects were 28 obese African American females, aged 9-14 years. Dual energy X-ray absorptiometry and meal test were performed at baseline and five weeks. Results. Approximately 30 of girls had metabolic syndrome. Serum 25OHD increased in both groups at five weeks [STAN: 20.3 ± 1.1 to 22.4 ± 1.1 (P ≥ 0.05) versus SPEC: 16.1 ± 1.0 to 16.8 ± 1.0 (P = 0.05)]. The STAN group, increased 25OHD concentration over five weeks (P 0.05), which was positively related to triglycerides (p ≥ 0.001) and inversely associated with total cholesterol (P ≥ 0.001) and LDL (P ≥ 0.001). The SPEC group, had increase in 25OHD (P = 0.05), which was positively related to fasting insulin (P ≥ 0.001) and insulin sensitivity while inversely associated with fasting glucose (P ≥ 0.05). The contribution of vitamin D status to metabolic syndrome parameters differs according to macronutrient intake. Improvement in 25OHD may improve fasting glucose, insulin sensitivity, and LDL; however, macronutrient intake warrants consideration. Copyright © 2012 Anna L. Newton et al.