Essential amino acid supplementation (EAA) was compared with supplementation by a mixture (KA) of keto-analogues of valine, leucine, isoleucine, methionine and phenylalanine, plus the four remaining essential amino acids in stable chronic uremics. When KA were given after EAA, urea appearance fell and N balance improved (9 studies). When EAA were given after KA (5 studies), urea appearance and N balance did not worsen significantly during the 4-9 days of observation. Seven patients, including one on chronic dialysis prior to therapy, were given KA for 3-9 months as outpatients. In three, renal function clearly improved. Five became asymptomatic for intervals of 3-8 months.