Glycyl-L-histidyl-L-lysine-copper (II) complex (GHK-Cu) is a naturally occurring tripeptide with potential healing properties. We studied the effect of GHK-Cu on the synthesis of glycosaminoglycans (GAGs) by normal human fibroblasts in culture. Cells were incubated with 3H glucosamine and 35S sulfate and the radioactivity of isolated GAGs was determined. GHK-Cu induced a dose-dependent increase of the synthesis of total GAGs secreted into the culture medium and those associated with the cell layer. The effect of GHK-Cu was biphasic with a maximal stimulation at 10(-9) to 10(-8) M. At higher concentrations, the rate of synthesis returned progressively to that of control cultures. Electrophoretic analysis of the different GAG populations showed that GHK-Cu preferentially stimulated the synthesis of extracellular dermatan sulfate and cell layer associated heparan sulfate. No influence of GHK-Cu on the synthesis of hyaluronic acid was observed. GHK-Cu stimulation of GAG synthesis may be one of the phenomenons implicated in the wound healing properties of the peptide.