Mg-based implants offer a promising alternative to commonly used permanent implants due to their biodegradability that eliminates the need for a follow-up surgery, along with the associated medical and economic risks. Several of the commercial Mg alloys for various applications including potential implant applications contain rare earth elements that are known to improve mechanical strength and corrosion resistance. However, it remains a significant challenge to better understand in vitro corrosion behavior of Mg–RE alloys and predict in vivo behavior, which is useful for biomedical applications, since in vitro corrosion rates tend to be significantly higher than those reported in vivo. In this work, we study the mechanical and corrosion behavior of two Mg–RE alloys, ZE41 and EZ33, at physiologically relevant temperature of 37 °C in 3.5 wt% NaCl and Hank’s solution. Tensile and compression tests were used to evaluate mechanical properties while electrochemical techniques were used to investigate the corrosion response. Both alloys demonstrated improved corrosion resistance in Hank’s solution which was attributed to the formation of a more protective surface film. In addition, the increased RE concentration positively impacted the corrosion behavior of EZ33 compared to ZE41 in both mediums.