The yields of cricket paralysis virus from two insect cell lines propagated in suspension culture were examined. Although Trichoplusia ni (TN368) cells produced more virus per cell than Drosophila line 2 (DL2) cells, the smaller DL2 cells reached a higher cell density. Thus the difference in production between TN368 and DL2 cultures was minimal. In mixed infections of Flock House virus and cricket paralysis virus (CrPV), CrPV was the predominant virus produced despite being present at a much lower multiplicity of infection.