Two new C₁₉ quassinoids 1 and 2 were isolated from the stem bark of Ailanthus excelsa along with three known quassinoids excelsin, glaucarubin and polyandrol. The last one is being reported for the first time from this plant. The structural elucidation is based on analysis of spectroscopic data. Excelsin has shown in vitro antimalarial activity.