Biodegradable aliphatic polyesters have numerous biomedical applications and their capacity to degrade in biological fluids provides the significant advantage of their removal. Three glycolide-containing aliphatic polyesters: a copolymer of glycolide and L-lactide (PGLA), a terpolymer of glycolide, L-lactide and epsilon-caprolactone (PGLCap) and a copolymer of glycolide, and e-caprolactone (PGCap) were tested to evaluate their biocompatibility towards osteoblasts and fibroblasts. Each of the polymer units was previously reported to have acceptable biological properties and good biodegradability, and PGLA is already used for biomedical applications. Here we report that both PGLCap and PGCap affected cell adherence, and compromised cell viability as estimated by flow cytometric analyses of apoptotic and necrotic cells. The two polymers enhanced also production of numerous inflammation-related factors: nitric oxide, matrix metalloproteinases (MMP-2 and MMP-9), and cytokines, including pro-inflammatory TNF-alpha, IL-1 beta, IL-6, and chemokines (IL-8 or MCP-1) attracting leukocytes. The effects of PGLCap and PGCap were similar despite the fact that they possess different characteristics: amorphous/smooth surface and semicristalline/rough surface, respectively. However, their common feature, distinctive from PGLA, is a presence of epsilon-caprolactone units in their structure. This compound is considered to be acceptably biocompatible but our data suggest that its copolymerization with glycolide and L-lactide does not provide satisfactory biocompatibility towards osteoblasts and fibroblasts. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 127: 3256-3268, 2013