In this study, some in vitro trials were carried out to evaluate the association between Scopulariopsis spp. fungi with Psoroptes cuniculi (Acari: Psoroptidae) and their potential pathogenicity to this mite species. After cultivation on Sabouraud dextrose agar with chloroamphenicol at 26 degrees C for 20 days and macro- and microscopical examinations, from P. cuniculi mites taken from some infested rabbits fungi belonging to the genus Scopulariopsis were isolated. Investigations were carried out to evaluate in vitro the potential pathogenic role of Scopulariopsis to P. cuniculi; to this aim, Scopulariopsis brevicaulis isolated from a cat was tested. In several culture media, the dose-dependent P. cuniculi mortality with different concentrations of S. brevicaulis and the ability of S. brevicaulis to penetrate inside the body of infected mites were evaluated. Results obtained demonstrated that, in the rabbit, Scopulariopsis fungi can be associated with P. cuniculi, and that S. brevicaulis can be an entomopathogen for P. cuniculi in a dose-dependent manner. A more rapid mortality of the mites and a quicker S. brevicaulis growth in plates containing rabbit serum with respect to all other media used were also found. S. brevicaulis demonstrated the ability to invade the body of P. cuniculi.