With the increasing incidence and mortality of cancer worldwide, there is an urgent need for new therapeutic approaches. Gene therapy is one such approach and preliminary data are promising. Viral and nonviral vector systems for gene delivery are available, but most of the current systems suffer from disadvantages such as low transfection efficiencies, in vivo instability, targeting problems, mutagenic potential and immunogenicity. Viruses of the Parvoviridae family, which are characterised by their oncotropism, oncosuppression, long-term gene expression and human apathogenicity, potentially offer advantages as viral vectors. This article evaluates their usefulness in gene therapy strategies for cancer.