The ubiquinone type of 38 species (41 strains) of Penicillium sensu lato and related teleomorphic genera ( Eupenicillium, Talaromyces, Thermoascus) was determined by RPPC or RPHPLC. In eight of the ten sections of Penicillium ubiquinone Q-9 was found as the main type. In sect. Geosmithia Q-10 and traces of Q-9 were demonstrated. In sect. Biverticillium (= sect. Simplicium) and its teleomorph Talaromyces Q-10(H2) was demonstrated; in one species an additional unidentified ubiquinone was found. Thermoascus has ubiquinone Q-9. The results and those of earlier authors support the idea that the genus Penicillium in the actually accepted broad concept is heterogeneous.