The Micro-Electro-Mechanical Systems (MEMS) have found wide application in medicine these days. Lots of them are used in form of implanted devices which usually demand complicated design and fabrication requirements. One of the most important issues for implantable MEMS is to be biocompatible. An implant usually needs a coating which can withstand the aggressive body fluid as well as being biocompatible. The coating must protect the sensor in the environment of the body. Meanwhile, it should not disturb the implant performance or damage the host tissue.This work aims to evaluate different biocompatible coatings on an implantable MEMS pressure sensor.The Effects of coatings on the sensors' sensitivity and thermal characteristics has been studied.