A preliminary examination of the crude methanol extracts of eight plant species collected from Sudan, revealed that only three plant species had a considerable in vitro antileishmanial activity on Leishmania major promastigotes at a concentration < 0.5 μg/mL. The plants Azadirchta indica, Maytenus senegalensis and Eucalyptus globulus gave IC₅₀ values of 11.5, 55 and 78 μg/mL, respectively. Extracts of Pseudocedrela kotscifye and Balanites aegyptiaca had a moderate biological activity, whereas extracts of Sonchous cornatus, Khaya senegalensis and Tamarindus indica failed to exhibit any significant antileishmanial activity against L. major at concentrations < 100 μg/mL. Liquid-liquid partitioning of the methanol extracts indicated that fractions of M. senegalensis in dichloromethane and ethyl acetate had the highest antileishmanial activity at 5 μg/mL; IC₅₀ values were 5.01 and 29.7 μg/mL, respectively. Preliminary phytochemical analysis of the dichloromethane fraction revealed terpenoids and traces of phenolic principles but no alkaloid, tannins or flavonoids were detected. As lymphocyte proliferation was inhibited by P. kotscifye and A. indica at higher concentrations (< 50 μg/mL) in the presence of phytohaemagglutinin (PHA), M. senegalensis had no significant toxic effect whereas S. cornatus, T. indica and K. senegalensis had a stimulatory impact on lymphocyte cells.