Cannabinoids, the active components of the cannabis plant, have merit as an anti-emetic and appetite stimulant in people with cancer. Recently, interest in cannabinoids has increased since reports that cannabinoids have anti-tumour activity. Although the mechanisms underlying these effects have yet to be fully elucidated, a broad spectrum of effects have been described, and cellular signalling pathways are known to be involved. There are currently two major cannabinoid receptors identified, whose roles in the activation of cell death remains controversial. Agonists to the type-2 receptor that do not have psychotropic effects have been used successfully in vitro, and we await the results of randomised trials using theses agents. The field of research into cannabinoids as anti-cancer agents is in its infancy, and more basic research is required before a good clinical agent can be realised. This article reviews the data currently available on this exciting group of potential anti-neoplastic agent.