Plants consist of numerous constituents known as phytoconstituents or bioactive components. Due to the therapeutic potential, these components are widely utilized in drug formulations. However the concept of medicinal plants as disease fighters is immemorial. In the traditional system of medicine, crude extract, paste and decoction formulations of plants were utilized to cure different ailments. But now with the availability of advanced technologies, it has become easier to use plants as medicines. Different phytochemical tests and techniques of HPLC and GCMS provide the accurate information regarding particular bioactive constituent present within the plant. This article looks at the important bioactive compounds present in different ethnomedicinal plants of Rajasthan used against various diseases like; diabetes, cancer, microbial infections, heart diseases etc.