Low glycaemic index diets reduce blood glucose and lipid levels in humans but glycaemic index values are only available for a small number of foods. Thus, we determined the glycaemic index of 102 complex carbohydrate foods in patients with diabetes. The values varied from 37 for bean thread noodles to 127 for Rice Chex cereal (p<0.001). There were no significant differences between the values of 14 different commercial leavened, wheat breads, which had a mean glycaemic index of 97. This supports the validity of using white bread as the standard food with an arbitrary glycaemic index of 100. There were significant differences between the glycaemic index values of individual foods in the following groups: rye breads, cakes, corn products, cookies, crackers, grains, pasta, potato, soups, legumes and breakfast cereals. Legumes and pasta tended to have low glycaemic index values. The glycaemic index values of the foods were weakly negatively related to their protein (r=-0.407; p<0.001) and dietary fibre (r=0.322; p<0.001) content but not fat (r=-0.054, ns). Thus, there are sufficient differences between the glycaemic responses of complex carbohydrate foods to make the glycaemic index classification a useful supplement to food tables in planning diets for patients with metabolic disorders such as diabetes or hyperlipidaemia.