Nyaya and Buddhism as the two important traditions of Indian Philosophical Thought distinguished themselves through a detailed inquiry into various aspects of Anumana. In both the traditions there flourished a long chain of logicians of great reputation and rofound scholarship. Particularly in the Buddhist tradition Dharmakirti distinguished himself, through his scholarly works, as a renowned logician and exerted influence alike both on his adversaries and followers. Although he has discussed a number of issues concerning Anumana in his different works, no systematic attempt has been made to formulate and present Dharmakirti's unified theory of Anumana in its various aspects. The present work undertakes to do this for the first time in the world of Buddhist scholarship. Giving a sketch of the conceptual framework of Dharmakirti's philosophy by way of background, it discusses epistemic, constitutive and regulative conditions of Anumana according to him and dealing with the validity and or soundness aspects of Anumana along with Hetvabhasas it may give rise to brings out their important implications not only for Dharmakirti's philosophy but also for Buddhist philosophy in general.