Two new lignans, interiotherins A (1) and B (2), along with two known lignans, angeloylgomisin R (3) and schisantherin D (4), were isolated from Kadsura interior. Their structures and stereochemistries were determined from spectral data. Compounds 1 and 4 inhibit HIV replication with EC50 values of 3.1 and 0.5 micrograms/mL, respectively.