The aims of the present study were to (a) evaluate the anthelmintic activity of 10 East African browse plant extracts, (b) examine their role in inhibition of Haemonchus contortus larval exsheathment, (c) establish relationship between inhibition of larval exsheathment and browse plant extract polyphenol composition. Acetone/water (70/30%) extracts of air dried leaves of Acacia etbaica, Cadaba farinosa, Capparis tomentosa, Dichrostachys cinerea, Dodonaea angustifolia, Euclea racemosa, Maerua angolensis, Maytenus senegalensis, Rhus natalensis and Senna singueana were used. The larval exsheathment inhibition assay (LEIA) was applied using H. contortus third stage larvae (L 3 ) and browse plant extract concentrations of 0, 150, 300, 600, 1200μg/ml in phosphate buffered saline (PBS). Data were analysed using the PROC MIXED procedure of SAS. Polyvinylpolypyrrolidone (PVPP) was used to evaluate whether polyphenols were involved in L 3 exsheathment inhibition. All browse plant extracts significantly (P ≤0.001) inhibited larval exsheathment in a dose dependent manner. The dose required to inhibit 50% of the larvae (EC 50 ) was highest in C. farinosa and lowest in E. racemosa and M. senegalensis. Significant differences (P