With the wide use of rare earth nanomaterials in industry, environmental control, and medicine with their unique properties, it has focused on the exposure of humans to the rare earth nanoparticles in recent years. Because of the similar properties of rare earth and calcium, rare earth nanoparticles can deposit in the bone and affect the osteogenic differentiation of bone mesenchymal stem cells (BMSCs). La(OH)(3) nanoparticles are widely used in the catalysis, sensor, electrode, and luminescent materials. However, there are few reports about the bioactivity of La(OH)(3) nanoparticles on the bone metabolism. In this work, three La(OH)(3) nanorods have been got by hydrothermal method, Long-, Medium-, and Short-La(OH)(3) nanorods, the lengths of which were of similar to 640, 255, and 80 nm, and the diameters of which were of similar to 85, 40, and 35 nm, respectively. All the La(OH)(3) nanorods showed no effect on BMSCs viability and the blood compatibility. But the osteogenic differentiation showed a significant difference in La(OH)(3) nanorods, in which Short-La(OH)(3) nanorods showed the highest promoting effect on osteogenic differentiation. The potential mechanism in the osteogenic differentiation caused by three La(OH)(3) nanorods was correlated with the different uptake efficiency in BMSCs and degradation in lysosome to form LaPO4. This work on La(OH)(3) nanorods provides the basic data for the development of lanthanum-based nanoparticles.