Quantum Dots have shown remarkable potentials in biomedical research. Herein, we reported the effects of CdTe quantum dots (QDs) and CdTe@SiO2 nanoparticles (NPs) on human embryonic kidney 293 (HEK 293A) cells with the aim of investigating their in vitro cytotoxicity. The CdTe@SiO2 particles were prepared by reverse microemulsion method. The structural morphology of the CdTe and hydrophilic silica-coated CdTe particles were characterized by transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) spectrometry and photoluminescence (PL) spectrometry. The in vitro cytotoxicity of CdTe QDs and CdTe@SiO2 nanoparticles was assessed in 293A cells using standard MTT assay, western blot and fluorescent microscopy. The results showed that the CdTe and CdTe@SiO2 particles were relatively uniform with the diameter of about 3.8 nm, 75 nm respectively. The cell viability and the adhesion ability were similar to the control 293A cells. The level of the fibronectin protein expression was decreased with the increasing concentration of CdTe while the no effects were observed on expression of beta-actin in CdTe as well as CdTe@SiO2 treated cells even at highest concentration of 45 microg/mL which demonstrated their good biocompatibility to 293A cells. The results indicate that the CdTe@SiO2 nanoparticles are attractive candidates for biological imaging studies as expected.