A phytochem. investigation on the aerial parts of Ajuga macrosperma led to the isolation of a new diterpenoid, namely ajugamacrin F (1), along with eight known compounds, including one diterpenoid (2), one norsesquiterpenoid (3), one triterpenoid (4), three sterols (5-7), and two benzene derivatives (8 and 9). Their structures were established via spectroscopic anal. and comparison with literature data. Compounds 2 and 5 were obtained from A. macrosperma for the first time, and compounds 3, 4, 6, 8, and 9 were firstly reported from the genus Ajuga. Furthermore, the chemotaxonomic significance of these isolates was discussed.