A survey is given of the possible types of seed dispersal in Cactaceae. Anemochory presumably occurs in only one genus, hydrochory is less rare and zoochory is common. A number of taxa apparently lack any dispersal mechanism (atelechory). Birds are frequently involved in zoochorous dispersal. Hydrochorous taxa all have seeds with a large, hollow hilum cup, which increases the floating capacity of the seed. A clear difference in the floating capacity between seeds with a small hilum cup and others with a large one is demonstrated.