The genus Zanthoxylum (Rutaceae) sometimes called 'prickly ashes' because of the shape of the leaves is represented by7 species in Kenya (l). Traditionally Zanthoxylum usambarense has been used to treat coughs, rheumatism, fever, sore throat, tonsilitis and chest pains; while Zanthoxylum chalybeum has been used for the treatment of malaria, colds and oedema in kwashiokor (2). The genus is a rich source of alkaloids, lignans, cournarins and other metabolites(3). In some species phytochemical investigation has revealed the presence of terpenoids and steroids (4). Other species have yielded amides most of which are aromatic (5). It is hypothesized that much of the pharmacological activity of these species may be attributed to their alkaloidal constituents because many pharmacologically active quarternary alkaloids have been found in various Zanthoxylum species (6). As a result, the focus in this work on Zanthoxylum usambarense and Zanthoxylum chalybeum is prompted by the aforementioned perspective.