This book will explore a species of Hawthorn endemically growing in Egypt, known as Crataegus sinaica. We had to cut a difficult journey in the mountains of Sinai, Saint Catherine, Egypt, to find this plant, and explore its secrets. The book will be covering many phytochemical and biological investigations used to reveal the hidden part of this plant. A lot has been done on this study, but still remains room for more investigations. Enjoy!!!