The aqueous extracts of 64 plant species, listed as animal- or insect-bite antidotes in old Thai drug recipes were screened for their activity against fibroblast cell lysis after Heterometrus laoticus scorpion venom treatment. The venom was preincubated with plant extract for 30 min and furthered treated to confluent fibroblast cells for 30 min. More than 40% efficiency (test/control) was obtained from cell treatment with venom preincubated with extracts of Andrographis paniculata Nees (Acanthaceae), Barringtonia acutangula (L.) Gaertn. (Lecythidaceae), Calamus sp. (Palmae), Clinacanthus nutans Lindau (Acanthaceae), Euphorbia neriifolia L. (Euphorbiaceae), Ipomoea aquatica Forssk (Convolvulaceae), Mesua ferrea L. (Guttiferae), Passiflora laurifolia L. (Passifloraceae), Plectranthus amboinicus (Lour.) Spreng. (Labiatae), Ricinus communis L. (Euphorbiaceae), Rumex sp. (Polygonaceae) and Sapindus rarak DC. (Sapindaceae), indicating that they had a tendency to be scorpion venom antidotes. However, only Andrographis paniculata and Barringtonia acutangula extracts provided around 50% viable cells from extract treatments without venom preincubation. These two plant extracts are expected to be scorpion venom antidotes with low cytotoxicity.