Orobanche cernuo Loefl. (O. cumana Wallr.; broomrape) is a troublesome parasitic weed of confectionery sunflower (Helianthus annuus L.). It is probably the most widespread species of of Orobanche spp., as it affects extensive areas of sunflower in Southern and Eastern Europe ancl Micldle East (Parker, 1936). In Spain this species was first detectcd in 1958 at Tbledo Province (Diaz-Celayeta,1974). Gonzalez-Torres, Jimenez Diaz and Melero-Vara (1982) reported the spreading of the infestation to Cuenca Province and to Fuente Piedra (Malaga Province). Recently O. cernua has also heavily infested another important confectionary sunflower area of about 20,000 ha at El Coronil (Sevilla Province) (Castejon, Romero-Munoz and Garcia-Torres, 1987). The area planted to confectionery sunflower has been drasticaly reducecl because of this parasite. O. cernua seeds are pear shaped and extremely small, from 250 to 390 um long and 150 to 240 um wide (Joel, 1987). The description of the surface characteristics of Orobanche spp. seeds is reported by Musselman and Mann (1976) and a key for their identification using these characteristics was developed by Joey (1987). The morphology of sunflower achenes is described by Knowles (1978), indicating the presence ofitraigtri hairs inclined outward or appressed in the pericarp or hull, and of an armor layer in some cultivars where the outer layer of cells developed in an unusual way, creating pointed cones or hooklets. Although some authors have previously suggested the possibility of O. cenua seed dispersal through sunflower achenes (Vranceanu, 1974) no dà1a have ever been reported to actually confirm it. The aim of this paper is to ieport stuclies that evidence ancl quantiff the dispersal of O. cernua through sunflower achenes.