IAA, IAN, accelerator α, and an ether-insoluble growth substance (designated as 'A') were found in alcohol extracts of healthy inflorescences ofBrassica napusL. and in smaller amounts in the malformed, parasitized inflorescences produced by plants infected withAlbugo Candida(Pers. ex Chev.) Kuntze. The total activity of diseased extracts (≡ 915 μg IAA/kg fresh weight) was only 61% of that of healthy ones. IAN accounted for approximately 86% of the total activity in both extracts.Brassicais thus a good source of IAN. Both IAA and IAN were identified by their chromogenic reactions, ultraviolet spectra, andRfvalues in two solvent systems. Alkaline hydrolysis of 'A' produced an ether-soluble, Ehrlich-positive spot with the sameRfvalue as IAA. The results are discussed briefly.