In this article, we present a Portable Intelligent ECG Monitor (PIEM) which can be used in a Wireless Remote Monitoring System. For the hardware design, Advanced RISC Machines (ARM) as well as ECG Application Specific Integrated Circuit (ASIC), GSM/GPRS and NAND Flash technologies is adopted. As for the software implementation, a real-time kernel called μC/OS-II and some related application programs were developed, among which an efficient and robust on-line ECG interpretation algorithm is included. A prototype of this device is finally accomplished and has been put into use in the clinical environment for one month. The results of the experiment show that this PIEM is clinically approved, accurate in its measurement, highly mobile, easy-to-use, durable and light-weight. Once this prototype is developed into product, there's no doubt that more and more cardiac patients will benefit from it.