An EtOH extract of the roots of Stephania abyssinica (Menispermaceae) contained stephavanine [2] and a new alkaloid, 4'-O-methylstephavanine [1]. Stephania abyssinica Walp. (Menispermaceae) is a creeper indigenous to southern and eastern Africa. The leaves of this plant are used as a purgative and emetic, whereas the roots are employed in the treatment of roundworm, menorrhagia, and boils (1). Previous phytochemical investigations of the plant material collected from Ethiopia and South Africa have revealed the presence of seven hasubanan alkaloids including stephavanine [2] (2,3). During our random screening of plant extracts for anticancer activity using a mechanism-based bioassay with DNA repair-deficient and repair-proficient yeast mutants (4), MeCOEt and EtOH extracts of S. abyssinica roots exhibited moderate activities. Several attempts to isolate the bioactive constituent(s) resulted in significant loss of bioactivity. However, our fractionation studies led to the isolation of two ester-ketal hasubanan alkaloids, 4'-O-methylstephavanine [1] and stephavanine [2], of which the former is new. Structure elucidation of 1 and assignments of ¹H- and ¹³C-nmr spectral data of both 1 and 2 are presented in this paper.