We describe here the ultrastructure of spermiogenesis and the mature spermatozoon of Fasciola hepatica (Trematoda, Digenea, Fasciolidae) by means of scanning (SEM) and transmission electron microscopy (TEM). Spermiogenesis in F. hepatica follows the general pattern of digeneans. However, this is the first report of a flagellar rotation of about 120° in Digenea. The mature spermatozoon of F. hepatica is a filiform cell of about 275 um in length. SEM and whole mount TEM revealed a helical pattern of axonemes around the sperm body. The spermatozoon presented the same ultrastructural organization as the congeneric F. gigantica. The most interesting features of the male gamete of F. hepatica therefore are the dorsolateral cytoplasmic expansion, the external ornamentation of the cell membrane and the spine-like bodies. We also analysed the distribution pattern of tubulin in the microtubular cytoskeleton of F. hepatica by means of monoclonal anti-tubulins (anti-alpha-tubulin, anti-beta-tubulin, anti-alpha-acetylated tubulin and anti-alpha-tyrosinated tubulin). These anti-tubulins labelled axonemal and cortical microtubules but not the central core of the 9+'1' trepaxonematan axoneme.