Platelet-derived growth factor (PDGF) released from platelets is one of the mitogens in serum, which plays a major role upon the cell biology, namely enhancing cell division and controlling of the maturation, especially upon the glial cell growth and its differentiation. Trapidil, which is an anti-PDGF agent, inhibits the effect of PDGF, especially the proliferative effects on the glial and tumoral cells in vitro. Previous studies suggested that the astrocytic proliferation stimulated by PDGF was inhibited by trapidil via the selective antagonism. Trapidil was not found to have a considerable effect on the prevention of nonpermissive astrocytes in this study. It should be theorised that trapidil, administered immediately even after the trauma, could not reach the injury site in effective measure because of secondary events such as edema and impairment of blood circulation. This suggestion should be another subject for studies concerning trapidil which is administered prior to the trauma.