Recent clinical data have emphatically shown the capacity of our immune systems to eradicate even advanced cancers. Although oncolytic viruses (OVs) were originally designed to function as tumour-lysing therapeutics, they have now been clinically shown to initiate systemic antitumour immune responses. Cell signalling pathways that are activated and promote the growth of tumour cells also favour the growth and replication of viruses within the cancer. The ability to engineer OVs that express immune-stimulating 'cargo', the induction of immunogenic tumour cell death by OVs and the selective targeting of OVs to tumour beds suggests that they are the ideal reagents to enhance antitumour immune responses. Coupling of OV therapy with tumour antigen vaccination, immune checkpoint inhibitors and adoptive cell therapy seems to be ready to converge towards a new generation of multimodal therapeutics to improve outcomes for cancer patients.