The ability of two groups of 13-93 bioactive glass scaffolds to support tissue ingrowth was evaluated after implantation for 4 weeks into subcutaneous pockets in the dorsum of Fisher 344 rats. One group of scaffolds (porosity = 85%; pore size = 100-500 microm) had a "trabecular" microstructure similar to that of dry human trabecular bone, whereas the other group had a "columnar" microstructure of oriented pores (porosity = 65%; pore width = 90-110 microm). Despite the lower porosity and pore width, the columnar scaffolds supported abundant soft tissue ingrowth (glycosaminoglycan and fibrillar stroma), whereas the trabecular scaffolds showed only limited tissue ingrowth. when seeded with mesenchymal stem cells (MSCs), both groups of scaffolds supported abundant tissue infiltration. Bone-like tissue was formed in both groups of scaffolds seeded with MSCs, but not in the scaffolds without MSCs. the new tissues integrated with the hydroxyapatite-like surface layer of the scaffolds which resulted from the conversion of the bioactive glass in the body fluids. the results indicate that the trabecular bioactive glass scaffolds seeded with MSCs, as well as the columnar bioactive glass scaffolds, seeded with MSCs or unseeded, could serve as substrates for bone repair and regeneration.