Immunotoxins and chimeric toxins are highly potent drugs designed for the treatment of cancer. Immunotoxins are composed of antibodies linked to a toxic substance. The antibodies enable the drug to bind specifically to distinct antigens on the tumor cell while the toxic moiety mediates cell death. Chimeric toxins are based on the same principle but contain other components for specific tumor cell targeting, e.g. cytokines or growth factors. The approval of the chimeric toxin denileukin diftitox (DAB389IL-2; Ontak) for the treatment of cutaneous T-cell lymphoma demonstrates the potential of immunotoxins and chimeric toxins for the treatment of cancer. New immunotoxins and possible treatment regimes are patented for commercial reasons before being published. Patents have become an indispensable requirement for pharmaceutical companies due to the high costs of drug development and clinical trials, allowing the protection of intellectual property and recovery of investments. This article reviews recent patents of immunotoxins and chimeric toxins. New agents are described and differences between certain patents are outlined to give an overview of the current situation of immunotoxins and chimeric toxins for the treatment of cancer.