The outer capsid spike protein VP4 is the main rotavirus cell attachment protein, but the cellular receptor used by rotavirus to establish a productive infection remains unknown. Sialic acid (SA) residues on the cell surface have been shown to be required for efficient binding and infectivity of animal rotaviruses (ARVs), but not of human rotaviruses (HRVs). Since the SA dependence of only a limited number of strains has been tested to date, in this study a larger number of strains were tested to further investigate the involvement of SA in rotavirus infectivity. Following treatment of African green monkey kidney cell (MA104) monolayers with neuraminidase, productive infection of rotavirus was measured by immunofluorescence. The infectivity of all 14 HRVs tested was SA-independent. Ten of 15 ARVs tested were SA-independent, while only five were SA-dependent. These results indicate that most ARVs, like HRVs, infect permissive cells in an SA-independent manner, probably by a common cellular receptor.