Ring-¿opening polymn. of e-¿caprolactone (e-¿CL) and L-¿lactide (LLA) was performed to impregnate ß-¿tricalcium phosphate (ß-¿TCP) scaffolds fabricated by robocasting. Concd. colloidal inks prepd. from ß-¿TCP com. powders were used to fabricate porous structures consisting of a 3D mesh of interpenetrating rods. e-¿CL and LLA were in situ polymd. within the ceramic structure by using a lipase and stannous octanoate, resp., as catalysts. The results show that both the macropores inside the ceramic mesh and the micropores within the ceramic rods are full of polymer in either case. The mech. properties of scaffolds impregnated by in situ polymn. (ISP) are significantly increased over those of the bare structures, exhibiting similar values than those obtained by other, more aggressive, impregnation methods such as melt-¿immersion (MI)¿. ISP using enzymic catalysts requires a reduced processing temp. which could facilitate the incorporation of growth factors and other drugs into the polymer compn., thus enhancing the bioactivity of the composite scaffold. The implications of these results for the optimization of the mech. and biol. performance of scaffolds for bone tissue engineering applications are discussed.