In Western Patagonia (Chile), sheep production is a key contributor to the local economy. Sheep production in Patagonia is largely based on the Corriedale, a dual-purpose breed used for apparel wool and prime lamb production. Over the last decade the relative value of sheep meat compared with wool production has greatly increased. Consequently, there is interest in using terminal sire breeds to improve growth and carcass quality in lambs. In view of this background a study is being undertaken to investigate the relative performance of four sire breeds across a range of sheep systems in Western Patagonia. This paper reports on the results from the first year of this two-year programme.