With the flourishing of multi-functional wearable devices and the widespread use of smartphones, MHN becomes a promising paradigm of ubiquitous healthcare to continuously monitor our health conditions, remotely diagnose phenomena, and share health information in real time. However, MHNs raise critical security and privacy issues, since highly sensitive health information is collected, and users have diverse security and privacy requirements about such information. In this article, we investigate security and privacy protection in MHNs from the perspective of QoP, which offers users adjustable security protections at fine-grained levels. Specifically, we first introduce the architecture of MHN, and point out the security and privacy challenges from the perspective of QoP. We then present some countermeasures for security and privacy protection in MHNs, including privacy- preserving health data aggregation, secure health data processing, and misbehavior detection. Finally, we discuss some open problems and pose future research directions in MHNs.