Cholesterol is known to play an important role in stabilising particular cellular membrane structures,so-called lipid rafts. For several viruses a dependence on cholesterol for virus entryand/or morphogenesis has been shown. Using flow cytometry and fluorescence microscopy wedemonstrate that Canine distemper virus (CDV) infection of cells was not impaired after cellularcholesterol had been depleted by the drug methyl-beta-cyclodextrin (MbCD). This effect wasindependent of the multiplicity of infection (MOI) and the cellular receptor used for infection.However, cholesterol depletion of the viral envelope significantly reduced CDV infectivity. Replenishmentby addition of exogenous cholesterol restored infectivity up to 80 percent. Thus,we conclude that CDV entry is dependent on cholesterol in the viral envelope. Furthermore, areduced syncytium formation was observed when the cells were cholesterol depleted during thecourse of the infection. This may be related to the observation that the CDV envelope proteinsH and F partitioned into cellular detergent resistant membranes (DRMs). Therefore, a role forlipid rafts during virus assembly and release as well is suggested.