Auraptene quantities in Tanaka's 77 Citrus species (including 14 varieties and cultivars), 5 Fortunella species, one Poncirus species, 27 hybrids between Citrus species, and 51 intergeneric hybrids between Citrus and Poncirus have been evaluated. The genus Citrus has been divided into eight groups. Auraptene is found in all of the species of Cephalocitrus group, a part of the species of Aurantium group, and most of the species of Osmocitrus group. The Citrus species contain a small amount of auraptene in the juice sacs compared with in the peels except for Henka mikan (C. pseudo-aurantium), Ichang lemon (C. wilsonii), and a Hassaku (C. hassaku)-pummelo hybrid (Okitsu No. 39), which contain large quantities of auraptene in their juice sacs (0.23, 0.52, and 0.14 mg/g, respectively). The Hong Kong wild kumquat (F. hindusii) alone contains auraptene in Fortunella species. All of the Citrus-trifoliate orange (P. trifoliata) hybrids as well as the trifoliate orange contain a large quantity of auraptene in both the peel (16.57-0.51 mg/g) and the juice sac (10.32-0.15 mg/g). These hybrids are almost inedible. The Iyo (C. iyo)-trifoliate orange hybrid (IyP269) is edible and contains auraptene in the peel (1.49 mg/g) and in the juice sac (1.73 mg/g). Citrus fruit products, for example, brand-named grapefruit juice and marmalade, retain about 0. 1 mg and 0.3 mg/100 g of auraptene, respectively.