Phytochemical investigation on the whole plant of Chloranthus japonicus (Chloranthaceae) led to the isolation and identification of three new lindenane-type sesquiterpenoid dimers, chlorajaponilides F-H (1-3), along with seven known ones (4-10). Their chemical structures were established by extensive spectral evidence. Compounds 1 and 2 are both dimeric sesquiterpenoids featuring a rare hydroperoxy group at C-5. All compounds were tested for their activities on wild type HIV-1 replication and compounds 1, 2, 5, and 9 were effective with EC50 values from 3.08 to 17.16 mu M. All these four compounds showed the same inhibitory effects on the two NNRTI-resistant HIV strains as on wild-type HIV-1 with EC50 change folds from 0.61 to 1.6 mu M. Furthermore, compounds 1, 5, and 9 exhibited inhibitory activities on HCV replication with the similar potency as their activities on HIV-1. Our finding may provide a clue to address the problem of HIV-1 and HCV co-infection. (C) 2016 Elsevier B.V. All rights reserved.