The invention relates to a process for the production of new immunobiological preparations for the diagnosis, prophylaxis and/or treatment of Candida guilliermondii infections. According to the invention one proceeds as follows:(a) a Candida guilliermondii strain is propagated under aerobic conditions at 24-42.degree. C. on a culture medium containing assimilable carbon and nitrogen sources, the resulting population(s) is (are) maintained under identical conditions for a prolonged period, therafter the fungus cells are separated from the culture, washed, ruptured mechanically, extracted, the extract is treated with a polar organic solvent, and the resulting precipitate is converted into an immunobiological preparation either as such or after further purification, or(b) a Candida guilliermondii strain is cultivated for 48-72 hours under aerobic conditions at 24.degree.-42.degree. C. on a culture medium containing assimilable carbon and nitrogen sources, the resulting culture is optionally propagated further to produce two or three new populations, then the fungus cells are separated from the culture, washed, ruptured mechanically, extracted, then, if desired, a polar organic solvent is added to the extract, and the resulting precipitate is converted into an immunobiological preparation either as such or after further purification, or(c) a Candida guilliermondii strain is cultivated for 48-72 hours under aerobic conditions at 24.degree.-42.degree. C. on a culture medium containing assimilable carbon and nitrogen sources, then the culture is killed, the killed cells are separated and converted then into an immunobiological preparation either as such or after purification.