One approach to the engineering of functional cardiac tissue for basic studies and potential clinical use involves bioreactor cultivation of dissociated cells on a biomaterial scaffold. Our objective was to develop a scaffold that is (1) highly porous with large interconnected pores (to facilitate mass transport), (2) hydrophilic (to enhance cell attachment), (3) structurally stable (to withstand the shearing forces during bioreactor cultivation), (4) degradable (to provide ultimate biocompatibility of the tissue graft), and (5) elastic (to enable transmission of contractile forces). The scaffold of choice was made as a composite of poly(dl-lactide-co-caprolactone), poly(dl-lactide-co-glycolide) (PLGA), and type I collagen, with open interconnected pores and the average void volume of 80 ± 5%. Neonatal rat heart cells suspended in Matrigel were seeded into the scaffold at a physiologically high density (1.35 × 10⁸ cells/cm³) and cultivated for 8 d in cartridges perfused with culture medium or in orbitally mixed dishes (25 rpm); collagen sponge (Ultrafoam™) and PLGA sponge served as controls. Construct cellularity, presence of cardiac markers, and contractile properties were markedly improved in composite scaffolds as compared with both controls.