The porous NiTi (pNiTi) samples were produced by sintering evaporation using Ti-50.8Ni (at.%) gas- atomized powders. The samples were analyzed by metallographic microscope and X-ray dispersive spectroscopy (XRD). A comparison of nickel (Ni) release and cytocompatibility between pNiTi and dense NiTi (dNiTi) was made. The results showed that the pNiTi has good mechanical properties. Ni releases from pNiTi in vitro and in vivo are more serious than those form dNiTi. The proliferation and differentiation of cells cultured with the pNiTi extracting liquid are significantly worse, and the rate of early apoptosis is higher. In conclusion, pNiTi is mechanically similar to bone, but pNiTi releases more Ni and interferes with cell proliferation and differentiation. A significantly cautious approach should be adopted when using it as a medical implant.