To enhance the partial knowledge on blackfly (Diptera: Simuliidae) fauna in Spain it is crucial to collect all the available data on this group to better understand their ecology and distribution over the years. This study presents data from samples collected along the Tormes river basin (western Spain) during the years 1988, 1989 and 1996 and then stored at the University of Salamanca. As a result of a research stay, a total of 19 species belonging to 3 genera (Prosimulium, Metacnephia and Simulium) and 5 Simulium subgenera (Boophthora, Eusimulium, Nevermannia, Simulium and Wilhelmia) were identified after examining 64% of the stored material, representing 35% of the species known from Spain. In addition, 14 species are reported for the first time in 3 provinces in the study area. Further sampling of blackflies is foreseen in the near future in order to check if the blackfly fauna composition determined in samples collected during the last two decades of the 20th century has changed. This aim gains in importance as a consequence of haematophagous species having been found, relevant for both public health and animal welfare, not only because of the discomfort caused by their bites but also because of their potential as vectors of disease-causing agents in animals and humans.