Dieldrin, one of the organochlorine pesticides (OCPs), induced the damages in neuroblastoma cells and DNA damages in lymphocytes. The ethanol extracts of A. sessiliflorus leaves were examined for the suppressive effects on the dieldrin-induced cell damages. Moreover, the extract was used to test whether it might inhibit the oxidative DNA damage of lymphocytes using Comet assay. The cell and DNA damage by dieldrin were suppressed in vitro upon treating A. sessiliflorus extract. This result suggests that A. sessiliflorus extract might be useful to reduce dieldrin toxicity.