The effect of surface hydrophilicity was induced from the amide units in the polyesteramide. The surface energies and compositions of the polyesteramides were studied by employing contact angle and interfacial tension measurements and ESCA analysis. Biodegradability was evaluated form various methods including activated sludge test, enzyme hydrolysis, and soil burial test, which determine the amount of evolved CO2, weight loss, and TOC values, respectively. It was found that the introduction of amide groups to the aliphatic polyester improved the biodegradability, although the increase of biodegradation rate was not directly proportional to the amide content. The biodegradability of aliphatic polyesters increased with the addition of amide functionality. Therefore, it can be concluded that the addition of appropriate contents of hydrophile enhanced the biodegradability of aliphatic polyesters as well as their physical properties. Also, the experimental results revealed the relation between hydrophilicity and biodegradability of polyesteramides. (C) 2003 Wiley Periodicals, Inc.