A tissue marking implant includes a matrix material and a dye marker. The implant, which can be formed entirely of bioresorbable material such as a collagen foam, is sized and shaped to replace excised tissue. The implant supports surrounding tissue upon implantation, while allowing for in-growth of fibrous tissue to replace the implant. According to various alternative embodiments, the implant is elastically compressible, or can be formed from self-expanding foam or sponges, and can be implanted through a cannula or by injection, as well as by open procedures. The implant can carry therapeutic and diagnostic substances. The dye marker leaches from the implant such that a surgeon, upon subsequent surgical intervention, visibly recognizes the tissue marked by the dye marker.