This work presents and evaluates methods employed to identify the potential of certain types of chemicals to adversely affect the skin. A variety of test methods are included such as tests for skin penetration, metabolism, irritation, the skin immune system, photo effects, skin cancer, and topical effects of retinoids and depigmenting chemicals. Tests for chemicals that affect the reproductive and nervous system are also included. Both animal and human tests that have been standardised and tests that are under development and employ animal alternatives are addressed in this book. Besides different testing methods, a rationale for accepting non-animal models and a review of some regulatory agency discussions about animal alternative tests are included.