Four abietane diterpenoids were isolated from the methanolic extract of the roots of Meriandera benghalensis and tested for their biological activity. Cryptotanshinone (2) and 17-hydroxycryptotanshinone (4) are known metabolites however the occurrence of tanshinone IIA (1) and przewaquinone A (3) from Meriandera benghalensis is reported for the first time. The four diterpenoids were identified by MS and one- and two dimensional NMR experiments. The isolated compounds were tested for their in vitro antiproliferative activity against three human cancer cell lines (a lung cancer (A-427), a urinary bladder cancer (5637) and a breast cancer (MCF-7) cell line) and for their antibacterial effect against three Gram-positive bacterial strains. All four abietanes showed potent cytotoxic effect against all cancer cell lines (IC50 between 1 and 8 microM) as well as antibacterial effect against the bacteria tested (MIC values between 33 and 70 microM).