This is the first paper to review the literature records on all pathog
ens and parasites of Opiliones on a global level. These organisms (bac
teria, fungi, protozoans, cestodes, trematodes, nematodes, arthropods)
are listed in phylogenetic order along with available information on
hosts, collection localities, life history, and taxonomic history. The
opilion hosts are also listed (by their currently accepted names) alo
ng with the names of their known pathogens and parasites. Diagnostic c
haracters and some taxonomic keys are provided for taxa which are rela
tively well know. Citations to other available keys are provided. Many
new host and distribution records are provided. Two fungi [Engyodonti
um aranearum (Cavara), Torrubiella pulvinata Mains] are removed from t
he list of pathogens of opilions and it is suggested that the original
hosts were misidentified spiders. Two new combinations are recorded i
n the Mermithidae: Agamomermis phalangii (Haldeman 1851), Agamomermis
truncatula (Rudolphi 1819). Agamermis incerta Steiner in Stipperger 19
28 is regarded as a nomen nudum. The type locality of the mite Leptus
lomani (Oudemans 1903b) is restricted to Corral (39-degrees-53'S, 73-d
egrees-25'W), Valdivia, Chile.