Many imaging techniques, such as optical imaging, magnetic resonance imaging, nuclear imaging, and ultrasound have been successfully utilized in clinical applications for the past decades. However, there is an urgent need to design new bioimaging probes because imaging of specific molecular pathways in vivo, particularly those that play key roles in disease processes, is hampered by the poor sensitivity and specificity with current low molecular weight imaging compounds. Recently, interdisciplinary research at the interface of polymer chemistry and the bioimaging sciences has led to the generation of polymer-based bioimaging probes for the diagnosis and treatment of disease. A combination of imaging modality and several biocompatible and/or biodegradable synthetic and natural polymers such as multivalent, branched, graft, and block copolymers, polysaccharides and dendrimers, has produced bioimaging probes which have prolonged plasma half-lives, enhanced stability, reduced toxicity, and improved target specificity. Bioimaging facilitates the integration of complex biological phenomena into the rapid visualization process in molecular levels, and are extending the applications into therapy and high throughput drug screening. This review describes the current advances in polymers for bioimaging and highlights their potentials in clinical applications.