Low-pressure membranes are often used for disinfection purposes. Using a simple bench-scale testing unit, several membranes were evaluated for their capability to remove microorganisms under specific conditions. Five hollow fiber modified polysulfone membranes ranging in molecular weight cutoff (MWCO) from 10,000 to 300,000 daltons and a 0.2 μm nominal pore size membrane were also evaluated. The 10,000 MWCO membrane removed less virus than the two 100,000 MWCO or the 300,000 MWCO membranes. The data from this study suggests that MWCO and specific flux may not, in all cases, be a good predictor of virus removal.