1. After oral administration of the muscle of skipjack tuna, about 90% of ingested anserine (Ans) was excreted quickly into urine as Ans (8%) and pi-methylHis (82%), indicating the fast decomposition of Ans into pi-methylHis. This was also the case for chicken muscle ingestion. 2. After eel muscle ingestion, carnosine (Car) excretion was only 1% of the ingested whereas almost no increase was found in His, a constituent of Car, indicating the re-utilization of this essential amino acid. Similar results were also obtained from beef and pork ingestion. 3. In all cases, the urinary excretion of these compounds reached a maximum within 7 hr after ingestion and returned to the level of meat-free diet within 40 hr.