Circadian rhythms of cells and organisms have been investigated at the physiologic and molecular levels in various research fields. Multiple activity and physiologic processes are coordinated with periodic light-dark cycles. The mammalian central circadian pacemaker is known to be located in the suprachiasmatic nucleus (SCN) of the hypothalamus. The central clock synchronizes circadian oscillations through the peripheral clocks found in the various tissues including the skin. Previous studies revealed that clock genes and proteins were expressed in keratinocytes, dermal fibroblasts, and melanoma cells. Several studies have demonstrated circadian rhythmicities of skin surface parameters including transepidermal water loss, sebum excretion, and skin temperature. One of the key features in the pathogenesis of acne is excessive sebum from the sebaceous gland. The mechanism of the oscillating sebum production and the regulatory system is unknown. In this article, I would like to review about the Role of circadian genes in skin physiology and skin disorders.