Platelet-activating factor (PAF) is a phospholipid produced by a variety of cells including platelets, endothelial cells, neutrophils, monocytes and macrophages. It has a wide range of potent biological activities including wound healing, physiological inflammation, apoptosis, angiogenesis, reproduction and long-term potentiation. This factor through modulation of intracellular pathways, can mediate various disease and malignancy processes. A wide range of pathological processes are affected by PAF including multiple sclerosis, CNS ischemia, meningitis, encephalitis, epilepsy and panic disorders, cardiac anaphylaxis, reperfusion injury and myocardial infarction, bronchial asthma, allergic rhinitis and pulmonary oedema, ulcers, acute pancreatitis and inflammatory bowel disease and many others. PAF can affect tumour development in several ways. Activated endothelium or cancer cells themselves may be the source of PAF production in the tumour microenvironment as well as expressing PAF receptor on their membranes. Several PAF-specific antagonists have been shown to be able to inhibit the malignant processes of cancer cells and further research in this field could develop novel cancer therapeutics.