Increased plasma levels of amino acids after ingestion of protein stimulate important biological systems, and especially changes in leucine concentrations has been linked to stimulation of muscle protein synthesis. ProGo®, a salmon protein hydrolysate, is a protein that has shown good absorption in ex-vivo systems. The aim of this study was to compare the leucinemia observed after ingestion of ProGo® against equal amounts of whey protein concentrate (WPC-80). The study had a randomized double-blinded cross-over design. Both products were given as 16 g protein doses to six young and healthy males. The first blood sample was collected just before ingestion of the protein, and thereafter at 20, 30, 45, 60 and 90 min. Blood samples were analyzed for glucose, insulin and two amino acids (leucine and glycine). The rise in leucine and glycine blood concentration generally mimicked the amino acid profile of the two proteins. A 15 min faster time to peak blood concentration of leucine was observed after ingestion of ProGo® (28 min; 224 μmol/L) as compared to WPC-80 (40min; 339 μmol/L), whereas no difference in time to peak was observed for glycine (ProGo® 38 min; 517 μmol/L; WPC-80 38 min; 284 μmol/L). The rapid increase in blood concentrations of amino acids after ingestion of both products resulted in an insulin response which reached similar peak concentrations (30 min; 124 μmol/L). To which extent the faster, but smaller, leucinemia observed after ingestion of ProGo® has the ability to stimulate muscle protein synthesis remains to be investigated.