This book attempts to provide some techniques for estimation of relative risk with application in clinical and epidemiological data. This is the reprint of the thesis submitted to the University of Delhi for the award of Ph.D. All the main contents of the book are published in National and International research journals. Analysis of clinical and epidemiological data has been of considerable interest for Biostatisticians for last many years. The relative risk is a useful measure of association between an infectious and chronic disease and plausible risk factors. Relative risk regression models are very effective tools for the analysis of the same. This book is going to be very useful for researchers especially Biostatisticians and epidemiologists.