Herbal medicinal drug may be single active constituent or entire herb source is considered as medicinal product. Most of herbal drug products used are group of constituents. Stable drug product maintains their identity, strength, therapeutic effect within given specifications throughout the shelf life. Herbal medicinal products are of different nature thermolabile to volatile. Stability testing of herbal products is a complicated issue because the entire herb or herbal product is regarded as the active substance, regardless of whether constituents with defined therapeutic activity are known. The stability testing of herbal products check the quality of herbal products which varies with the time under the influence of environmental factors, such as temperature, humidity, light, oxygen, moisture, other ingredient or excipient in the dosage form, particle size of drug, microbial contamination, trace metal contamination, leaching from the container, etc. and also provide statistics for the determination of shelf lives. Therefore evaluation of the parameters based upon chemical, physical, microbiological, therapeutic and toxicological studies can serve as an important tool in stability studies.