This pioneer book in the area of Basic and Clinical Epidemiology in Indian sub-continent gives an introduction to principles and practice of Basic and Clinical Epidemiology in a simple and lucid manner. Book starts with factors leading to disease causation and details the interaction between Agent, Host and Environment. An introduction to the environmental and occupational epidemiology is given. The book attempts to integrate the Basic Epidemiology taught in didactic lectures with the process and of Clinical Research in Practice