Evidence indicating the natural occurrence of the auxin substance, phenylacetic acid (PAA), in a range of crop plants has been obtained from paper chromatography followed by bioassay and from HPLC and GLC analysis of acidic ether extracts from vegetative shoots of these plants. Confirmatory evidence for the presence of PAA in tobacco shoots has been obtained from GC‐MS analysis. Quantitative estimation of the relative amounts of the two auxins, IAA and PAA, in the different shoot extracts was achieved by paper chromatography followed by gas chromatography. The amount of PAA in all six plants was found to be several times greater than that of IAA and calculation of average internal concentrations revealed that PAA is present in vegetative shoots at physiologically active concentrations. Present knowledge of the growth‐regulating activity of this new natural auxin is discussed.