This paper describes the in vitro and in vivo anthelmintic activity of Artemisia brevifolia in comparison with levamisole. In vitro studies revealed anthelmintic effects of crude aqueous (CAE) and methanol extracts (CME) of Artemisia brevifolia (whole plant) on live Haemonchus contortus as evident from their paralysis and/or mortality at 6 h post exposure. For in vivo studies, the whole plant of Artemisia brevifolia was administered as crude powder (CP), CAE and CME at graded doses (1, 2 and 3 g kg(-1) body weight (b.w.) to sheep naturally infected with mixed species of gastrointestinal nematodes. Maximum reduction (67.2%) in eggs per gram (EPG) of faeces was recorded on day 14 post treatment in sheep treated with Artemisia brevifolia CAE at 3 g kg(-1) b.w. It was found that, although, Artemisia brevifolia whole plant possesses anthelmintic activity against nematodes, it is not comparable with levamisole (99.2% reduction in EPG) at any of the doses tried in this study. However, increase in EPG reduction was noted with an increase in the dose of Artemisia brevifolia administered as CP, CAE and CME. The graded dose response suggested further studies on a larger number of animals on higher doses than those used in the current study.