The prostaglandins (PGs) and thromboxanes (TXs) produced are then released outside the cells by various stimuli and bind individual receptor systems that are coupled to the G-protein system. Eight kinds of receptors for prostanoids such as PGE (including isoforms ; EP1, EP2, EP3 and EP4), PGD, PGF, PGI and TX, have been demonstrated. Recently, knockout mice lacking prostanoid receptors have also been developed. We characterized the skin of PG receptor knockout mice. Macroscopically, we observed slight abnormal hair growth in PGE receptor knockout mice, but did not find any histological difference in the skin between knockout and control mice. Moreover, we did not find any difference in the expression of erythema and swelling and the number of sunburn cells after UVB irradiation to the ears between knockout and control mice. There were also no significant difference in the expression of primary or allergic contract dermatitis induced by PMA or DNCB.Wound healing after experimental ulcer formation in the skin is slightly delayed in PGE and TX receptors knockout mice. These results suggest that even if one PG receptor is deficient, other PG receptors can compensate the function of lacked receptor and totally no serious defects are expressed in knockout mice skin. Abnormal hair growth in PGE receptor knockout mice are under investigation.