This is an introductory book on Biophysics meant for undergraduate students of universities and technical institutions. The first part of the book deals with organ systems and describes the principles of physics in the processes of locomotion, blood and fluid flow, respiration, audition and vision. The second part deals with cellular and molecular biophysics and covers, in depth, molecular forces and structure of biomolecules, dynamics of biomembranes, near-equilibrium thermodynamics, photosynthesis and cellular respiration and nerve excitation, etc. The book is designed in such a way that it can be used by both Mathematics and Biology groups.