The nutritional state of 32 patients after (mean 66 months) colon interposition due to benign oesophageal disease was examined. Forty-four per cent of the patients had depleted iron stores (low serum ferritin concentration). Serum iron and blood haemoglobin concentrations were lower (P less than 0.001) in those with low than in those with normal serum ferritin concentration (115 +/- 12 g/l and 15 +/- 5 mumol/l vs 135 +/- 12 g/l and 23 +/- 9 mumol/l). Most very low blood haemoglobin concentrations (less than 110 g/l) were found in patients with depleted iron stores. Eighteen patients had serum albumin concentrations slightly below (35-39 g/l) the normal range, and two other patients had values less than 35 g/l. The patients had less dietary iron (13 +/- 6 mg/d) than age- and sex-matched controls (19 +/- 7 mg/d), but the intake of patients with depleted iron stores (12 +/- 5 mg/d) was similar to that of patients with normal iron stores (14 +/- 6 mg/d). Symptoms and/or the replacement of colon graft anti- or isoperistaltically did not have any significant association with the nutritional status, only slightly reduced blood haemoglobin and serum albumin concentration were found among the symptomatic patients and the patients with an antiperistaltic graft. Iron therapy and protein supplements, eg, from milk, egg, soy and meat, are recommended as the dietary treatment. To improve the nutritional status a short intra-abdominal colon graft loop anastomosed to the proximal stomach instead of long loop with an antral anastomosis of the present patients is suggested.