Vitamin K was discovered as nutrient of blood clotting. There are two main types of vitamin K, vitamin K1, and vitamin K2. Although the structure of vitamin k is stable but also, there are differences between them. Vitamin k1 is mainly present in dark green leafy plant; while vitamin k2 present in animal and fermented plant. There are different sources of vitamin k. The normal human body is required about 200µg/day from vitamin k in both forms. Vitamin k1 can easily converted into vitamin k2.There is big difference between work of types of vitamin k, where each one responsible for special job. Vitamin k play important role in various metabolic process; vitamin k especially k2 play important role in protect the body from heart attack , in addition to reduce the development of osteoporosis and bone disease in combination with vitamin D and calcium. Vitamin k responsible for increase the secretion of male sex hormone and infertility. Vitamin k is consider one of the most important vitamin, it can save human from death as result of precipitation of calcium on arteries. Due to the importance of vitamin k, this article will discuss vitamin k, its presence, and role in different diseases.