AbstractGlycemic index (GI) and glycemic load (GL) are measures of the metabolic effects of dietary carbohydrates. The higher their value, the greater the glucose and insulin responses. Raised insulin levels are associated with endometrial cancer and with its risk factors including obesity, diabetes and hypertension. To study the role of the GI and GL we analyzed the data of two hospital‐based case–control studies on endometrial cancer conducted between 1988–98 in Italy and Switzerland, including a total of 410 women with incident, histologically confirmed endometrial cancer and 753 controls admitted for acute, non‐neoplastic diseases. A food frequency questionnaire was used to assess the subjects usual diet and to derive estimates of dietary GI and GL. The odds ratios (OR) of endometrial cancer, after adjustment for major risk factors, for the highest versus the lowest quintile of dietary GI and GL were 2.1 (95% confidence interval [CI] = 1.4–3.2) and 2.7 (95% CI = 1.8–4.2), respectively. The associations were stronger in older women, in those with higher body mass index and in hormone replacement therapy users. Our study supports the hypothesis of a direct association between GI and endometrial cancer risk. © 2003 Wiley‐Liss, Inc.