Chronobiology, the science of temporal rhythms in biological systems, is a relatively new field. Biological clocks coordinate our physiological and behavioral functions and interactions with our environment. Based on the sun as our primary external synchronizer, the circadian rhythm is probably the most pronounced biorhythm influencing our daily functions. Insights into this field have revealed numerous endogenous clocks composed of an intricate network of regulatory feedback loops, the complexity of which is currently little understood. Biological clocks can also be found on the cellular level, with the genes aptly termed period, timeless, clock, etc. In this chapter, examples of chronobiological rhythms, primarily circadian rhythms, found in the skin on both the functional and cellular levels will be described.