Limited studies have conducted on the association between carbohydrate intake, glycemic index (GI), glycemic load (GL), and BC risk among Middle Eastern women. Our objective was to examine whether intake of carbohydrates, GI and GL would lead to more risk of BC among Iranian women. In this case-control study, 136 women with histologically confirmed BC and 272 control women were recruited. Dietary intake was assessed using a validated 168-item food frequency questionnaire (FFQ) from which GI and GL were estimated. We calculated Odds ratios (OR) using logistic regression. The multivariate OR for the highest vs. the lowest quartile was 2.49 (95% CI 1.28-4.82; P trend = 0.005) for GI with a significant trend. OR for GI and GL among postmenopausal women were 4.45 (95% CI 1.59-12.47; P trend = 0.002) and 4.15 (95% CI 0.87-19.67; P trend = 0.03), respectively. OR for GI among women with reduced vegetable intake was 13.55 (95% CI 3.90-46.99; P trend <0.001). Our data suggest that high GI and GL play an important role in the risk of BC particularly among postmenopausal woman.