The operational complexity and extremely high cost in a conventional biomedical imaging device usually prevent patients from monitoring their health conditions or obtaining primary diagnosis themselves via a cheap and flexible way. The increasing demand for convenient medicine at low cost has significantly stimulated the innovations in extending the capabilities of a mobile phone as a basic tool in biomedical imaging area, whose low cost and easy access make it a rather perfect option for miniaturization and simplification of conventional medical devices. Combined with other technologies, the mobile phone is playing an increasingly important role in biomedical diagnosis and treatment owing to its imaging function. Such newly emerging frontier raises many challenging fundamental as well as very practical issues waiting for solving. Based on reviewing recent patents and some related researches, this article is dedicated to drafting this new biomedical imaging area and presenting a comprehensive evaluation on the latest achievements on developing the mobile phone based biomedical imaging technology. Important issues either in theory or hardware designs will be presented. Some important technical investigations worth of pursuing in the near future will be suggested. Particularly, direct optical or functional image acquisitions enabled from mobile phones will be illustrated with typical implementations in teledermatology, telemedicine, microscope, endoscope and ultrasound, X-CT, infrared, ECG mapping, biometric authentication, etc. Remote image detection using mobile phone as the imaging terminal is also proposed. Challenges for further development will be pointed out. From the technical routes as clarified and outlined in the present article, it can be found that there is plenty of space in the coming era of mobile phone based biomedical imaging technology.