The interaction between nanoparticles (NPs) and cells has been studied extensively, but the effect of particle shape on cell behavior has received little attention. Herein three different shaped monodisperse mesoporous silica nanoparticles (MSNs) of similar particle diameter, chemical composition and surface charge but with different aspect ratios (ARs, 1, 2, 4) were specially designed. Then the effects of particle shape of these three different shaped particles on cellular uptake and behavior were studied. The results indicated that these different shaped particles were readily internalized in A375 human melanoma (A375) cells by nonspecific cellular uptake. Particles with larger ARs were taken up in larger amounts and had faster internalization rates. Likewise, it was also found that particles with larger ARs had a greater impact on different aspects of cellular function including cell proliferation, apoptosis, cytoskeleton formation, adhesion and migration. These results show that nanoparticles should no longer be viewed as simple carriers for biomedical applications, but can also play an active role in mediating biological effects. Therefore, our findings may provide useful information for the development of new strategies for the design of efficient drug delivery nanocarriers and therapeutic systems and provide insights into nanotoxicity.