(18β)‐glycyrrhetinic acid (1), and the cytotoxicity of some derivatives was investigated by photometric SRB assays employing several human tumor cell lines. In summary, (18β)‐1 is slightly more cytotoxic than its (18α) epimer 4, but itscytotoxicity is negligible. Higher cytotoxicity was observed for the esters 2 and 5 and for the 3‐O‐acetylated esters 3 and 6. Cytotoxicity was improved dramatically when the