Introduction: Human body is composed of five universal elements together known as ‘Pancha Mahabhuta’. As this body is moment to moment decaying, these five elements also get denuded every moment. Their continuous replacement through food, which is also composed of these five universal elements, is considered to be the most important aspect for maintenance of health. To maintain the homeostasis of the body, this ingested food under-goes three physical and chemical changes - first by digestion, then by absorption and ultimately by metabolism. Agni is the prime factor for regulation of all these three processes. Aims and Objectives: So, this study was conducted to evaluate the concept of digestion, absorption and metabolism as described in Charaka Samhita as well as to evaluate the role of Agni as prime factor for all these physiological processes. Discussion: The pro-cess of digestion has been described in two different levels in Charaka Samhita, at gross level it has been termed as Ahara Paka and at minute level it has been termed as Avastha Paka. With the help of Jatharagni, at the end of these two processes, the ingested food which is heterogeneous in nature ultimately converted into a homogenous substance known as Ahara Rasa. Then this Ahara Rasa, which is composed of five Mahabhutas, gets absorbed within the tissue elements of body which are also composed of these five Mahabhutas, as per their predisposition. This process of absorption is regulated by five types Bhutagnis specific to each Mahabhutas and has been termed as Bhutagni Paka. The ultimate transformation of food occurs in terms of Dhatu Paka which can be correlated with the process of metabolism. The Ahara Rasa transformed into Rasa Dhatu, which is con-sidered as the most primary tissue element. Then this Rasa Dhatu transforms into Rakta Dhatu and the process of gradual transformation continues till the formation of Shukra Dhatu. This whole process of Dhatu Paka is regulated by seven types of Dhatwagnis specific to each type of Dhatu. Conclusion: The Ayurvedic concept of Ahara Paka, Bhutagni Paka and Dhatu Paka has a very scientific approach to the whole process of digestion, absorption and metabolism respectively. The modern scientific understanding of all these procedures is based on many hypotheses which are being changed time to time. The Ayurvedic concept of the above three processes paves a way for new dimension in interpretation of all these procedures and should be validated by modern sci-entific parameters in near futures.