A guinea pig partial thickness skin excistoti model wx used to evaluatc the effects of recombinant human PDGF-BB, 1′17GF-AA, ECF, and bFGF on granuLition tissue (neodermis) formation. These growth factors tended to increcisr the thickness of the granulation tissue bed when assesstd histcilogitally at day 7. Using only four animals per group, PDGF-BB at 30 and 100μg/ml consistently and significantly incwaseil the thickness of the granulation bed 2–3 limits that of control. Except for the increased thickness, the granulation tissue appmred normal. I'DGF-AA and EGF also significantly increased the granulation tissue thickness, and bFGF gave indications of an effect. Therc was no evidence of synergistic effects bthwxi PDGF-BB, EGF, and/or bFCF.