When luxuriantly growing Cuscuta parasitised Vicia faba at the time of flowering, fruit setting of the host was generally completely inhibited. When the host was infected in a later stage of development Cuscuta seriously interfered with further growth of pods. The process of translocation of 14C-assimilates from a photosynthesising leaf to other parts of the host and to the parasite was analysed. The process of assimilate withdrawal by Cuscuta turned out to be so efficient that usually only negligible amounts of “‘C-assimilates – or nothing at all – found its way into pods and seeds of the parasitised host.