Ayurveda has described three basic physiological constituent dosha, dhatu and mala for the existence of human body. Among them, seven dhatus form the structural units of the body. The functions of dhatus are dharana (to support) and poshan (to nourish). Dhatus undergo continuous construction and degeneration to maintain a state of equilibrium of the body. Majjadhatu is the sixth dhatu to be formed after asthi dhatu in uttrottardhatuposhan cycle. Bone marrow can be considered as a part of majja dhatu playing a significant role in erythropoiesis. Acharya Sushrut has mentioned about saraktameda and majja. Asthi (bone) and sandhi (joints) are the foundation of majjavahasrotas. The quantity of majjadhatu is one anjali. This manuscript is an attempt to explore the physio-anatomy of majja dhatu based on physiological functions described in ayurveda classics. For which the basic material has been collected from the ancient classics with the available commentaries as well as text books of contemporary modern medical science. KEY WORDS: Bone Marrow, Majja, Majjavahasrotas, Medas, Saraktameda.