We demonstrate, for the first time, that the (Fe0.75B0.15Si0.1)100 − xNbx (x = 0, 1 and 3 at.%) metallic glasses without toxic and allergic elements exhibit excellent apatite-forming ability in simulated body fluids (SBF), which is expected to be a new generation of biomaterials in stents and orthopedic implants. For the alloys without any surface treatment, spherical particles corresponding to octacalcium phosphate are spontaneously nucleated and precipitated throughout the alloy surface after immersion only for 1 day, indicating that the present alloys possess an unusual high bioactivity.