Polyvalent hyperimmune plasma (HP) with high-titers of virus neutralizing (VN) antibody to porcine reproductive and respiratory syndrome virus (PRRSV) strains was produced in gilts and used to passively immunize 3 week old piglets. The piglets were subsequently challenged with live virus. Results showed delay of viremia, decrease in live virus titers, decrease in gross lung lesions, or delay in transmission to naïve, non-immunized sentinel pigs.