Acid-insoluble ash (AIA) and acid-detergent lignin (ADL) were evaluated as internal markers in digestibility studies with African Grey parrots (Psittacus erithacus erithacus). Apparent metabolizable energy, corrected for nitrogen (N) retention (AMEn), nitrogen retention (NR), and apparent digestibility of dry matter, organic matter, crude protein and crude fat of a commercial seed mixture, sunflower seed, and a commercial pelleted parrot diet were determined using either the method of total collection of feed and excreta or using the marker technique. Both AIA and ADL presented unrealistic negative digestibility values for whole seed diets due to the higher concentration of marker found in the calculated feed intake than in the excreta. This study illustrates the necessity to determine nutrient concentration in feed refusals in digestibility studies with parrots due to the feeding habits of these birds. However, AIA as marker produced digestibility values that, although higher (P < 0.05), showed similar or less variation than the method of total collection when applied to pelleted parrot diets in which feed refusals contain roughly the same nutrient concentration as the feed offered.