Partial molar volumes, V2oand partial molar heat capacities Cp,2ohave been determined in aqueous solution at 25°C for the dipeptides glycyl-L-asparagine, glycyl-DL-threonine, glycyl-DL-serine and glycyl-DL-phenylalanine. These results, along with those for some other dipeptides of sequence Gly-X, were used to estimate side chain contributions to V2oand Cp,2o. For these dipeptides both V2oand Cp,2owere found to be a linear function of the respective thermodynamic property for the amino acid X. The contributions of the glycyl units to V2oand Cp,2oof the dipeptide are discussed