Two-thirds of the world’s population is thought to obtain their medical care from sources outside conventional med­icine, such as Ayurveda, Unani, Kampo, Latin American folk systems, traditional Hawaiian medicine, Homeopathy, Siddha, etc. [1]. Despite differences in the cultures, lan­guages, geographical locations, worldviews, and health beliefs of the people from where they originated, these medical systems have common characteristics. These include (i) individualized patient diagnosis and treatment; (ii) the use of complex interventions, often involving mul­tiple botanical products; (iii) treating the “whole” patient (physical, mental, and spiritual) instead of just to a single pathology; and (iv) an emphasis on disease prevention. Complementary and alternative medicine (CAM) is a group of diverse medical and healthcare systems, practices, and products that are not presently considered to be part of conventional medicine [2]. These practices are defined as “complementary” when used together with conventional medicines and as an “alternative” when they are used to replace them [3]. The currently practiced allopathic medi­cal system is not complete for all health problems, and sometimes, the therapeutic approaches aim to provide symptomatic relief rather than a definite cure. This chapter mainly focuses on the Ayurveda, Siddha, Unani, and Homeopathy systems of medicines.