Values for digestibility of nutrients in diets or feed ingredients fed to pigs are determined by nutrient intake and nutrient excretion in feces or ileal digesta. Ileal nutrient digestibility is determined using an indigestible marker because complete quantitative collection of ileal digesta is usually not possible. As a consequence, analysis of marker concentration in digesta is critical for accurate calculation of digestibility coefficients. Therefore, a sufficient adaptation period before initiation of ileal digesta collection is also important to make sure that the concentration of the marker in digesta is constant. It is, however, not known if the adaptation period is different among different markers. Therefore, an experiment was conducted to test the hypothesis that adaptation is needed to have constant marker concentrations in ileal digesta from pigs. The second objective was to test the null-hypothesis that apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of AA digestibility and the basal endogenous losses of AA are constant regardless of the indigestible marker used.