Pimpinella essential oils and isolated compounds were screened for their inhibitory activity against NF-kappa B mediated transcription in SW1353 cells. Twelve oils were effective in inhibiting NF-kappa B mediated transcription. Especially the roots of P. corymbosa, P. tragium and P. rhodanta showed potent activities with IC50 values of 2, 3 and 6 mu g/mL, respectively. Five pure compounds, 7 (4-(2-propenyl)phenylangelate), 12 (4-(3methyloxiranyl)phenyltiglate), 17 (4-methoxy-2-(3-methyloxiranyl)phenyl isobutyrate), 18 (4-methoxy-2-(3methyloxiranyl)phenylangelate) and 21 (epoxy pseudoisoeugenol-2-methylbutyrate) inhibited NF-kappa B mediated transcription with IC50 values of 5.5, 1.2, 0.01, 3.6 and 11 mu g/mL, respectively. None of the compounds were cytotoxic to mammalian cells. These findings add significant information to the pharmacological activity of Pimpinella species and their beneficial effects and use in disease prevention especially those related to inflammation. Copyright (c) 2007 John Wiley & Sons, Ltd.