The combretastatins are a group of anti-mitotic agents isolated from the bark of the South African tree Combretum caffrum. The most potent member is combretastatin A-4, and this compound together with a phosphate pro-drug form have already progressed through into clinical trails for the treatment of solid tumours. What makes this class of compounds rather more interesting than other anti-mitotic agents is that they are also angiogenesis inhibitors, and are being evaluated for their efficacy in the treatment of diabetic retinopathy which is the biggest single cause of blindness They are thus of considerable contemporary interest.