This invention is directed to a continuous process for producing viral particles by providing in a perfused growth medium a population of viable virally infected non-lytic cells, and removing medium containing said cells at a rate to maintain the steady-state log-phase growth of cells remaining in the perfused growth medium. The invention is also directed to a process for purifying retroviral particles by passing a solution comprising the retroviral particles and contaminants through an anion exchange resin, and eluting the retroviral particles from the resin. The preferred exchange resin is a tentacle anion exchange resin.