The composition of a leaf oil sample from Fortunella japonica was investigated by GC(RI), GC-MS and 13C-NMR. A special attention was brought to germacra-1(10),5-dien-4α-ol. Indeed, identification of diastereoisomers α and β of germacra-1(10),5-dien-4-ol has been the subject of controversy in the literature. We report here for the first time 13C NMR data of the α isomer. The occurrence of germacra-1(10),5-dien-4α-ol (1.1-7.7%) was observed in the five Fortunella leaf oils investigated (japonica, margarita, hindsii, obovata and crassifolia).