Quercetin and kaempferol rhamnodiglucosides are characteristic compounds of Camellia sinensis. Their structures were determined as quercetin-and kaempferol-3-O-[β-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 6)-β-D-glucopyranosides]. Reversed phase HPLC methods for preparative isolation and analytical separation of both compounds were developed. The structural elucidation of the compounds by means of NMR spectroscopy, fast atom bombardment MS and GC-MS of the sugar moieties is described. Black tea contains 0–0·95 g kg−1 quercetin rhamnodiglucoside and 0·05–1·25 g kg−1 kaempferol rhamnodiglucoside.