In the course of our study to clarify the mechanism of physiological abscission of the young fruit of Citrus unshiu, we are investigating the hormonal balance in the young fruit. Khalifah et al. have suggested the occurrence of the non-indolic auxin, citrus auxin, in the fruit and seed of Citrus species. Goren and Goldschmidt have reported the occurrence in Citrus sinensis of some promoters, which are different from indoleacetic acid (IAA) and citrus auxin, and quite recently Goldschmidt et al. the identification of IAA in Citrus stem. We report here the isolation of IAA and indoleacetamide (IAM) from the very young fruit of Citrus unshiu. On the other hand we could not find any indication for the occurrence of the so called "citrus auxin." The young fruit (10 kg) was harvested one week after full bloom and was extracted with peroxide-free ether and successively with methanol by use of blender. Each extract was separated into fractions A, B, C and D by solvent extraction. Fractions A, C and D were separately purified by specific procedures, with purification steps guided by the Avena curvature test and TLC sprayed with Ehrlich reagent. Successive purification of fraction A afforded 3.5 mg of crystalline powder identified as IAA by comparison of TLC Rf values, gas chromatography retention times, UV and mass spectra with authentic IAA. Fraction C was shown to contain IAA (content 3 mg estimated by Avena curvature test and gas chromatography) and yielded 13 mg of crystalline IAM identified by comparison with an authentic sample. Fraction D yielded another 40 mg of IAM and 90 mg of a tryptophane-containing peptide. This experiment disclosed that the young fruit of Citrus unshiu contains 0.5~1 mg/kg (ca. 0.2 μg/fruit) of IAA and 5 mg/kg (ca. 1 μg/fruit) of IAM. Any other fractions except those containing IAA and IAM did not reveal appreciable auxin-like activity, indicating the absence of citrus auxin.