The effects of magnesium on the growth and proliferation of human embryonic stem cells (hESCs) was explored to advance magnesium as an implant biomaterial. When magnesium ions from magnesium salt were added to the culture media at 10, 100, 250, 500, 750, and 1000 ppm (0.4, 4, 10, 20, 30, 40 mM) the rate of increase in viable cell coverage over time was higher for the larger doses of magnesium salt. Thus, the addition of magnesium ions exerted a positive effect on viable cell coverage. When hESCs were cultured with pure magnesium metal strips through transwell inserts, the cells underwent an initial increase in viable cell coverage, followed by rapid cell death within the first 24 hours. This initial increase in viable cell coverage corresponded to the colonies dispersing and losing their tightly packed morphologies. The cell death may be attributed to an increased alkalinity in the culture media incubated with the magnesium metal strips. In conclusion, since the degradation of magnesium results in both magnesium ions and OH- ions (an increase of pH), controlling the degradation of magnesium to obtain the perfect balance of ions is critical for advancing magnesium as an implant biomaterial.