Objective To study effect of diclofenac sodium on content of prostaglandin E 2 KC/MC ratio and hyperpigmentation of the full-thickness skin autografts. Methods Content of PGE 2 was determined by radioimmune analysis method, and kinetic changes of KC/MC ratio were observed with histological and histochemical methods. Results In the operation control group, increase of KC/MC ratios was accompanied by of PGE 2 content at the early stage of the experiment; and the KMR became smaller than that in normal control group at the end of the experiment. While in the diclofenac soduim group, KMR was reduced due to the less damage of MC at the early stage, with decrease of PGE 2. Accordingly, KMR became larger at the late period of the experiment, and color of the autografts became lighter. Conclusion Application of diclofenac sodium on the grafts just after transplantation may reduce the damage of inflammation to the epidermal melanin units, control their proliferation and decrease the value of KMR, which lightens the color of the grafts.