Recent study demonstrated that a particular derivatization approach can remarkably improve the stability of freshly etched porous Si (PSi) films under aqueous conditions. In contrast, the dramatically different anticipated response of such films to physiological environments are assessed. Derivatized material is exposed to simulated body fluid (SBF) and its degree of corrosion, oxidation, and calcification monitored by scanning electron microscopy, Fourier transform infrared spectroscopy, and secondary ion mass spectrometry, and compared with that of hydride-passivated layers of the same microstructure.