Giovanni Canestrini (1835–1900) was the pioneer of arachnology in Italy, who published the first catalogue of Italian spiders and a total of 87 papers in the field. His interests covered almost all the Italian arachnid orders, although in the last part of his life he focused on acarology, in which he became a leading world expert. The remains of Canestrini's arachnological collection deposited in the Zoology Museum of Padova University are represented by spiders (about 850 tubes), mites (438 microscope slides, 115 tubes), harvestmen (120), pseudoscorpions (63), scorpions (19) and solifuges (1). The collection is now part of a large revision project aiming at better understanding and clarifying the scientific heritage of Canestrini, including an inventory of the type material from Canestrini and other European arachnologists who contributed to his collection (e.g., T. Thorell). The first results of the collection revision outlining different arachnid orders and highlighting the occurrence of type material are presented here. Brief historical information on Canestrini and his pupils is also provided.