Bioactive glasses are known to have the ability to regenerate bone, and to release ionic biological stimuli that promote bone cell proliferation by gene activation, but their use has been restricted mainly to the form of powder, granules or small monoliths. Resorbable 3D macroporous bioactive scaffolds have been produced for tissue engineering applications by foaming sol-gel-derived bioactive glasses. The foams exhibit a hierarchical structure, with interconnected macropores (10-500 mum), which provide the potential for tissue ingrowth and mesopores (2-50 nm), which enhance bioactivity and release of ionic products. The macroporous matrices were produced by the foaming of sol-gel glasses with the use of a surfactant. Three glass systems SiO2, SiO2-CaO and SiO2-CaO-P2O5 were foamed using various concentrations of surfactant, in order to investigate the effect of surfactant concentration and composition on the structure and properties of the hierarchical construct. (C) 2003 Kluwer Academic Publishers.