In the case-control study we compared dietary habits among 108 patients with small (< or = 5 mm, n = 26), medium (5-9 mm, n = 48) or large (> or = 10 mm, n = 34) colorectal polyps with 35 healthy age- and gender-matched controls. A food record by weighing during 5 consecutive days was performed. The intake of fat was significantly higher among the patients, in contrast to a significantly lower intake of carbohydrate, dietary fibre and iron, compared with controls. The intake of vitamin C and calcium was shown to be lower among the patients, but this was significant only for women. There was a tendency among the patients to consume a lower-antioxidant, fibre and cereal fibre diet, and a calcium-rich and more cholesterol-rich diet with increasing size of polyps. The patients with the smallest polyps tended to consume less starch. Our results are too preliminary to draw conclusions with regard to the influence of nutritional factors on the size and growth of polyps. However, our risk factors for the presence of polyps are in agreement with previous studies. Further studies taking into account the size of the polyp are needed to corroborate our findings.