SUMMARYAspergillus rugulosus, a member of the A. nidulans group of fungi, produces a number of complex phenolic metabolites. In the course of studies towards the elucidation of the biosynthesis of these compounds, we have undertaken an investigation of linkage which involved conventional genetic markers together with phenol-biosynthesis characters. This led to the observation that there was a direct relationship between a morphological character, designated ' flufTy ', and the production of a particular complex phenolic compound.