Chemical analysis of representatives of about thirty genera of Lejeuneaceae has shown that the terpenoid and flavonoid content of the Lejeuneaceae is basically comparable to that of other Hepaticae and quite diversified. Among the terpenoids detected, some are common throughout the family (elemenenes, germacrenes), others are distributed more restrictedly and are indicative of evolutionary relationships among genera, e.g. borneols (Nipponolejeunea), pinguisanines (Acrolejeunea complex), striatenes (Ptychanthoideae, Omphalanthus complex), calamenanes ( Lopholejeunea) and labdanes (Ptychanthus, Tuzibeanthus). Flavonoids are present in smaller amounts than terpenoids and comprise some compounds unique to bryophytes (lutonarin, kaempferol-3-methylether). The genus Omphalanthus stands out by its total inability to biosynthesize flavonoids. At the species level the chemical constitution may vary considerably and in some species evidence for the existence of chemical races was detected.