The effects of the addition of Zn element on the microstructures, mechanical properties and bio-corrosion properties of Mg-3Ca alloys are investigated. The microstructure and X-ray diffraction topography indicate that as-cast Mg-3Ca alloys are composed of primary Mg and eutectic (alpha-Mg + Mg2Ca) phases, while Mg-3Ca-2Zn alloys are constituted of primary Mg and eutectic (alpha-Mg + Mg2Ca + Ca2Mg6Zn3) phases. Mechanical properties results show that the element Zn could improve both tensile strength and elongation of Mg-3Ca alloys. The ultimate tensile strength is enhanced by 22%. Meanwhile, the corrosion resistance is increased by the addition of Zn element. It is thought that the presence of Ca2Mg6Zn3 phase mainly contributes to these improvements. Mg-3Ca-2Zn alloy provides moderate strength and excellent corrosion resistance for biomedical application. (C) 2010 Elsevier B.V. All rights reserved.