A new betalain has been isolated from fruits of Rivina humilis and identified as the betaxanthin humilixanthin, the 5-hydroxynorvaline-immonium conjugate of betalamic acid. Its structure was elucidated and characterized by 'H NMR spectroscopy, FAB mass and GC/MS spectrometry, UV/Vis absorption spectroscopy, highperformance liquid chromatography, thin-layer chromatography and electrophoresis. The structure of the amino acid moiety 5-hydroxynorvaline (2-amino-5-hydroxyvaleric acid) was unambiguously confirmed by comparison with synthetic reference material. Humilixanthin was alsodetected in fruits of Phytolacca acinosa and P. bogotensis, in petals of Delosperma luteum, Lampranthus aurantiacus, L. peersii, Portulaca grandiflora, and in the yellow-coloured root of Beta vulgaris.