The enthalpies of solution of glycyl-L-alpha-alanine (gly-L-ala), glycyl-L-alpha-leucine (gly-L-leu), glycyl-L-alpha-serine (gly-L-ser), and glycyl-L-alpha-aspartic acid (gly-L-asp) have been measured in water and in aqueous urea solutions with molalities from (0.25 to 3.0) mol . kg(-1) at T = 298.15 K. The experimental results were used to calculate the enthalpic coefficients of the interactions between dipeptides and urea molecules in water based on McMillan-Mayer's model. (C) 2009 Elsevier Ltd. All rights reserved.