Poxviruses are cell-associated viruses that can be grown in adherent- or suspension-cell cultures or chorioallantoic membranes of embryonated hen's eggs. The main principle of isolating the virus is to mechanically lyse infected cells. The virus can then be semipurified by centrifugation through a sucrose cushion. Further purification can be achieved with a sucrose gradient. This chapter describes methods for the preparation of large-scale growth and purification of the virus.