A new alkaloid named herquline has been isolated from culture broth of Penicillium herquei Fg-372 by solvent extraction and silica gel chromatography. The molecular formula of herquline has been determined as C19H26N2O2 on the basis of elemental analysis and its high resolution mass spectrometry. The compound does not possess antimicrobial activities, but weakly inhibits blood platelet aggregation induced by adenosine diphosphate.