. Ileal amino acid digestibility and estimates of endogenous amino acid losses in pigs fed rapeseed meal, sunflower meal and soybean meal. Can. J. Anim. Sci. 80: 495-506. Four commercial samples of rapeseed meal (RSM), four of sunflower meal (SFM) and nine of soybean meal (SBM) were analysed and their ileal N and amino acid (AA) digestibilities in growing pigs were studied. Each batch was tested on four castrated male pigs weighing between 40 and 100 kg and fitted with an end-to-end ileo-rectal anastomosis. True ileal digestibility (TD) of AA was calculated by correcting apparent ileal digestibility (AD) for basal endogenous AA losses, measured by means of a protein-free diet. For RSM and SBM, total endogenous gut AA losses were estimated by a multiple regression model and real ileal digestibility (RD) of AA was calculated. In RSM, average TD of lysine, threonine and methionine were 70.7, 73.2 and 86.0%, respectively. These values were 80.0, 81.8 and 91.9%, respectively in SFM and 90.5, 86.8 and 93.0%, respectively, in SBM. In SBM, TD decreased (P < 0.05) with increases in the ratio of dietary acid detergent fibre (ADF) to AA contents. Expressed as g kg -1 dry matter (DM) intake, total endogenous gut N losses reached 4.7 to 6.4 for RSM and 1.9 to 3.5 for SBM. For SBM, they increased (P < 0.001) with dietary ADF concentration and RD of most AA decreased (P < 0.05) with the increase in the ratio of dietary neutral detergent fibre (NDF) to AA concentrations.