Nature is full of nonlinearities, responsible for a great variety of responses in natural systems. Physiological rhythms constitute a central characteristic of life, which is motivating the analysis of dynamical aspects related to natural systems. Natural rhythms could be either periodic or irregular over time and space and, each kind of dynamical behavior may be related to both normal and pathological physiological functioning. This review article presents an overview of nonlinear dynamics and chaos concepts useful for the analysis of biomedical system. After that, it is presented an overview of dynamical aspects related to different biomedical systems. Cardiovascular rhythms, brain rhythms, cellular and molecular rhythms are discussed from a dynamical approach pointing some characteristics of normal and pathological responses