To determine the amount of endogenous amino acids in budgerigars (sekiseiinko, Melopsittacus undulatus), as the first step of evaluating amino acid requirements, three experiments were conducted. In Experiments 1 and 2, transit time of the feeds through the digestive tract in budgerigars was studied. The birds were given free access to a corn-based diet containing 50% barium sulfate in Experiment 1, and Japanese millets (hie, Echinochloa utilis) with 0.5 ml of 50% barium sulfate solution in Experiment 2. At intervals of 0.5 to 2 hr, roentgenography was conducted to identify the position of the barium sulfate in the digestive tract. The results showed that the transit time of pellets and millets in the digestive tract was within 24 and 27 hr, respectively. In Experiment 3, to determine the amount of endogenous amino acids in budgerigars, the excreta were collected for 24 hr, from 27 to 51 hr after fasting. The excreta were hydrolyzed with 6 N hydrochloric acid at 110 degrees C for 22 hr for the determination of amino acids by HPLC. The endogenous Ala, Arg, Leu, Lys, Phe and Val were estimated to be 34.9, 36.8, 18.5, 20.3, 15.3 and 18.9 micrograms/day/BW0.75, respectively, which were higher than those in adult roosters.