The possibility of vaccination against schistosomiasis has been repeatedly proposed and promised for so many years that, for those not actively engaged in the field, a degree of scepticism might seem justified. However, as in many other fields, the problem is one of time-scale rather than feasibility, requiring decades rather than years to achieve the eventual goal of a product suitable for general use in man. Over the past few years, steady and-substantial progress has been made. This has recentlv been reviewed in detail bv BERG~UIST (19901, and the iresent article summarizes