Metabolic effects of pancreatectomy and hypophysectomy are investigated in the yellow American eel, Anguilla rostrata, fasted for 6 months. The results are compared with the findings in freshly captured eels subjected to the same operations. In intact animals, fasting causes a statistically significant decrease in serum amino acid nitrogen (AAN), serum urea, and relative liver weight, and an increase in serum free fatty acids (FFA), serum cholesterol, and tissue hydration. Serum glucose, liver and muscle glycogen, liver and muscle fatty acids, and abdominal fat stores do not show significant alterations. The absence of diabetes mellitus after pancreatectomy, seen in previous studies, is confirmed. However, pancreatectomy affects fewer parameters in fasting eels than in fed ones. After hypophysectomy, the situation is similar; only serum AAN shows an impact of the operation in fasted eels. As in freshly captured eels, surgical stress seems to affect almost all metabolic parameters. It appears that the smaller impact of both pancreatectomy and hypophysectomy in fasted eels reflects the reduced role of hormones in the state of lowered metabolism.