<jats:p>Homoglutathione (hGSH: γ‐glutamyl‐eysteinyl‐β‐alanine) was purified from seeds of <jats:italic>Phaseolus coccineus</jats:italic> L. cv. Preisgewinner, using anion‐exchange chromatography and Cu<jats:sub>2</jats:sub>O precipitation. Quantitative and specific determination of this thiol is possible by high‐performance liquid chromatography (HPLC) after monobromobimane derivatization. The enzymatic recycling assay based on yeast glutathione reductase (EC 1.6.4.2) can also be applied, but only to samples containing either hGSH or glutathione (GSH), since enzyme reaction with hGSH is 2.7 times faster than with GSH. Using the very sensitive HPLC method, the thiol content of leaves, roots and seeds of several legumes was investigated. Although GSH and hGSH were found in all plants analysed, the GSH/hGSH ratio varied greatly within the different tribes as well as within the different organs of plants of one species. In seeds and leaves of Vicieae, only traces of hGSH were found beside the main thiol GSH, whereas in roots the hGSH content exceeded the GSH content. The Trifolieae contained both tripeptides and in the tribe Phaseoleae, hGSH predominated by far.