This is an introductory text on Biophysics meant for undergraduate students of our universities and technical institutions. The first part 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 bio molecules, dynamics of biomembranes, near-equilibrium thermodynamics, photosynthesis and cellular respiration, nerve excitation, etc. In the second edition, we have further added a discussion on nano-bio-machines and on medical imaging (CT-SCAN and MRI). The book is designed in such a way that it can be used by both Mathematics and Biology groups. New to the second edition: chapters on: Physics of Nano-biomachines Medical Imaging.