Herpes simplex virus-1 (HSV-1) is an enveloped, double-stranded DNA virus that has been used with modification as an oncolytic virus against a number of tumor types. Modifications that make HSV-1 replication--conditional, i.e., selectively divide in replicating cells make it fulfill a prerequisite criteria for oncolytic viruses. Other appealing features of HSV-1 as an oncolytic virus include its large, modifiable genome; its sensitivity to antiviral agents, such as ganciclovir; and its lack of host cell integration. Here, we review the methods of HSV-1 engineering, through traditional recombination techniques as well as through bacterial artificial chromosome (BAC) technology. We then describe protocols for titering, amplification, and purification of engineered HSV-1-derived oncolytic viruses.