<jats:title>Abstract</jats:title><jats:p>Free amino acids from various plant tissues and fungal mycelia were extracted with buffered ethanol (75%, v/v) in 0.5% 2‐amino‐2‐methyl‐1‐propanol‐hydrochloride pH 11.0. Following removal of proteins and other high molecular weight components by ultrafiltration, free amino acids in the extracts were dried, derivatized with phenylisothiocyanate and analysed by high performance liquid chromatography using a Waters Pico‐Tag column. Arogenic acid, a non‐aromatic amino acid precursor of phenylalanine and tyrosine, was not detected although both aromatic amino acids were quantitated in all plant and fungal extracts. Nevertheless, arogenic acid in the mycelium of a triply‐blocked mutant of<jats:italic>Neurospora crassa</jats:italic>was readily detected. It is proposed that the absence of arogenic acid in plant extracts suggests that this intermediate does not accumulate in the metabolic pool thereby negating a possible regulatory role during aromatic amino acid biosynthesis.