This study is part of a research project, which seeks to develop techniques for inducing histogenesis of differentiated tissue on three-dimensional porous substrates. It is concerned with developing a simple, dependable method of coating polyurethane foam with collagen and with defining the characteristics of the collagen coat. The collagen, extracted from bovine tendon, was applied as a one percent dispersion. The collagen coat was directly measured to be 7 to 1A thick by a scanning electron microscope. The coating consisted of intertwining fibrils running in the same general direction. About 8% of the sponge surface area was covered. Adherence tests utilizing the above dispersion, and a glutaraldehyde cross-linked dispersion revealed the collagen coat to be invulnerable to lysis by the tissue or culture medium. The coated sponges exhibited greater invasion by the cells than the uncoated. Elongated cells lying along the coated fibers of the sponge indicated that migration was not random, but rather guided by the collagen, little can be said about improved histological reconstruction of the tissue without a much more extensive sampling. Investigations into optimum sponge pore size are not completed; preliminary results suggest that a pore size of .4 millimeters or larger yields the best growth characteristics.