A survey of 170 Australian species of Cyperaceae belonging to 35 genera has confirmed that this family has a highly characteristic tlavonoid pattern in leaf and inflorescence. Aurone pigments, the most distinctive family constituents, were found in the leaves of 25 % of the sample and in the inflorescences of 40 %. Sulphuretin was found for the first time in the family, in Carex appressa. Flavones, such as tricin and luteolin, are very common; in addition, a variety of methyl ethers were detected. Luteolin S-methyl ether was found in further genera, while luteolin 'I-methyl ether, diosmetin and acacetin were detected for the first time in the Cyperaceae. Flavonols and their methyl ethers occurred in over one-third of the species, particularly in the leaves, being especially well represented in the genera Fuirena, Gahnia, Lepidosperma and Mesomelaena. Myricetin was found only twice, in two Baumea species. The 3 desoxyanthocyanidin carexidin was found in the inflorescences of eight species, i.e. in 5 % of the sample. Taxonomically, the results are mainly of interest at the generic and specific level, where the patterns sometimes show useful correlations with morphology. At the tribal level, the Sclerieae are the most distinctive, with higher than average frequency of flavone C-glycosides, llavonols, proanthocyanidins and aurones, and lower than average frequency of flavones.