Three new daphnane diterpenoids, altadaphnans A-C (1 - 3), have been isolated from the aerial parts of Ddphne altaica, together with 7 known daphnane diterpenoids. Their structures were elucidated on the basis of lD and 2D NMR data. Altadaphnans A-C (1 - 3) showed significant antiproliferative activity against human lung carcinoma cell line A549.