Toddalidimerine, a new dimeric benzophenanthridine alkaloid, has been isolated from the roots of Toddalia asiatica. On the basis of spectral analysis it has been characterized as 1,3-(8-hydrochelerythrinyl-8′-hydro-N-norchelerythrinyl) acetone. The presence of dihydrochelerythrine and 8-acetonyldihydrochelerythrine has been confirmed in this plant. © 1981.