Input vaccinia virus deoxyribonucleoproteids with buoyant densities (in CsCl) very similar (if not identical) to those of viral cores have been found in large cytoplasmic structures in which viral DNA replication takes place. The deoxyribonucleoproteids consist of at least five major and two minor core proteins and viral DNA which is protected against DNase digestion. It is suggested that viral core-like deoxyribonucleoproteids rather than released DNA are used in vaccinia-infected cells both for delayed-early gene transcription and viral DNA replication.