Surface resistance to nonspecific protein adsorption, cell/bacterial adhesion, and biofilm formation is critical for the development and performance of biomedical and analytical devices. Significant needs and efforts have been made in the development of biocompatible and bioactive materials for antifouling surfaces, but much of the work retains an empirical flavor due to the complexity of experiments and the lack of robust theoretical models. In this review, two major classes of nonfouling materials (i.e. hydrophilic and zwitterionic materials) and associated basic nonfouling mechanisms and practical examples are discussed. Highly hydrated chemical groups with optimized physical properties of the surface, along with appropriate surface coating methods, are the keys to developing effective and stable nonfouling materials for long-term biomedical applications. The zwitterionic polymers are promising nonfouling biomaterials due to the simplicity of synthesis, ease of applicability, abundance of raw materials, and availability of functional groups. (C) 2010 Elsevier Ltd. All rights reserved.