Anisaldehyde characterized in the seeds of Pimpinella anisum L. (Umbelliferae), also known as aniseed, was found to inhibit the oxidation of l-3,4-dihydroxyphenylalanine (l-DOPA) by mushroom tyrosinase (EC 1.14.18.1) with an ID50 of 43 μg/mL (0.32 mM). The inhibition kinetics analyzed by a Lineweaver−Burk plot established anisaldehyde to be a noncompetitive inhibitor for this oxidation. On the basis of this finding, various related analogues were also tested in order to gain new insights into their structural functions. Keywords: Anisaldehyde; aniseed; tyrosinase inhibitor; l-DOPA; noncompetitive inhibition; Schiff base formation