Poly(beta-malic acid) and its ester derivatives are biodegradable polyesters, which are candidates for innovative drug delivery systems. XPS and ToF-SIMS have been used to investigate the surface chemical structure of poly(beta-malic acid), its butyl and benzyl ester derivatives, and a range of their copolymers. The XPS analysis of these polymers showed a good correlation between the experimental and theoretical compositions. The peak-fitting routine applied to the C 1s spectra provided functional group information. The ToF-SIMS analysis of these materials showed characteristic fragmentation patterns for each home-and copolymer, which consisted of ions diagnostic of the polymers under investigation. This combined use of ToF-SIMS and XPS is shown to provide a detailed insight into the surface chemical structure of the poly(beta-malic acid) polymers.