Luminescent markers play a key role in imaging techniques for life science since they provide a contrast mechanism between signal and background. We describe a new type of marker using second harmonic generation (SHG) from noncentrosymmetric BaTiO3 nanocrystals. These nanoparticles are attractive due to their stable, non-saturating and coherent signal with a femtosecond-scale response time and broad flexibility in the choice of excitation wavelength. In this paper, we report the use of nanoparticles for cell imaging. We first stabilized the BaTiO3 nanoparticles in suspension and characterized the optical properties. We also demonstrated the functionalization of BaTiO3 nanoparticles by conjugating IgG antibody on the surface of the nanoparticles. These functionalized nanocrystals are capable of specific labeling the antigens of interest. © 2009 SPIE-OSA.