Effects of coprophagy and coprophagy preventing device on iron bioavailability were evaluated in two experiments. In Experiment 1, rats were fed diets with FeSO4, spinach, bran cereal or cornmeal as the iron source. The rats in each diet group were fitted with collars, sham-collars or not fitted with collars (control). In Experiment 2, rats were fed diets with FeSO4 or green peas as the iron source and were fitted with collars, tail cups, sham-collars or not fitted with any device (control). Preventing coprophagy reduced hemoglobin regeneration efficiency (HRE) of rats fed bran cereal, green peas, spinach or cornmeal diets by 26 (P less than .05), 24(P less than .05), 22(P less than .05) and 11% (not significant), respectively. Preventing coprophagy in rats fed FeSO4 diet did not significantly reduce HRE. Sham-collaring reduced (P less than .05) HRE of rats fed the FeSO4 diet by 12 and 13% but did not significantly affect HRE in rats fed food iron sources. It was more convenient and effective to prevent coprophagy with collars than with tail cups. Differences in bioavailability between food and FeSO4 iron due to coprophagy may be explained based on two gastrointestinal nonheme iron pools, complexed and highly soluble.