In order to exert an effect, either local or systemic, putative beneficial dietary substances have to survive at least to some extent the digestive process within the gastrointestinal tract. For that purpose, five castrated male pigs (100 ± 2 kg mean live b.w.) fitted with T-shaped ileal cannulas were used to determine the recovery up to the terminal ileum of various non-nutritional factors (NNF) from legumes (defatted soybean, raw lupin, raw chickpea and raw or autoclaved kidney beans). Kidney bean lectin (PHA) recovery within the small intestine ranged between 2.5 and 4.8 mg from 5.96 mg ingested. Two different methods were used to determine ileal digestibility of protease inhibitors (PI) in pigs. According to the enzyme-linked immunosorbent assay (ELISA) method, apparent digestibility of Kunitz trypsin inhibitor and Bowman–Birk inhibitor for pigs fed the defatted soybean-based diet were 0 and 58%, respectively. On the other hand, the apparent digestibility of PI along the small intestine, expressed in terms of trypsin inhibitory activity, was 96, 98 and 95% of activity in the diet, while data expressed in terms of chymotrypsin inhibitory activity were 95, 99 and 79% of activity in the diet for defatted soybean, raw chickpea and autoclaved kidney bean diets respectively. Differences found in ileal digestibility values of PI using both methodologies, ELISA and enzymatic inhibition, might be explained by the detection of inactive forms by specific antibodies. Intestinal apparent digestibility of phytate was 0% for defatted soybean and autoclaved kidney bean diets, whereas values for raw lupin and chickpea diets were 4.1 and 24.5%, respectively. In conclusion, significant amounts of several NNF survived the passage through the stomach and small intestine of cannulated pigs, which might have biological relevance. Copyright © 2006 Society of Chemical Industry