A deeper understanding of the mechanisms underlying the regulation of immune responses together with the discovery of methods to identify tumour antigens have provided a strong foundation for the development of cancer immunotherapies. The recognition that multiple components of the immune system can effectuate tumour destruction has fostered the crafting of several strategies to augment anti-tumour immunity. These approaches involve the stimulation of tumour antigen-specific T lymphocyte and antibody responses, the augmentation of multiple components intrinsic to innate immune responses and the selective destruction of the tumour vasculature. A decisive factor in the crafting of these schemes has been the development of high efficiency gene transfer systems. These technologies render possible the genetic modification of a variety of cells playing critical roles in the evolution of anti-tumour immune responses; such modifications can dramatically enhance the levels of anti-tumour immunity. In this review, I will discuss the pre-clinical background underlying some of the current Phase I patient studies and highlight some of the intriguing early findings from these clinical investigations.