In an ethnopharmacological screening of selected Nepalese medicinal plants, the inhibitory effect on lipid peroxidation of 36 methanolic extracts of 28 different plant species were evaluated using bovine brain phospholipid liposomes as model membranes. The most potent inhibitor with an IC50 value of 0.93 microg/ml was the extract obtained from the bark of Clerodendrum indicum. The extracts obtained from Aglaia roxburghiana fruits, Euonymus pendulus barks and Emblica officinalis fruits were also active and inhibited lipid peroxidation with IC50 values of 10, 12 and 13 microg/ml, respectively. The most active extracts were from indigenous plants traditionally used to treat inflammatory diseases.