Using internet-based software known as 1000Minds, choice-experiment surveys were administered to experts and farmers from the Irish sheep industry to capture their preferences with respect to the relative importance - represented by part-worth utilities - of target traits in the definition of a breeding objective for sheep in Ireland. Sheep production in Ireland can be broadly separated into lowland and hill farming systems; therefore, each expert was asked to answer the survey first as if he or she were a lowland farmer and second as a hill farmer. In addition to the experts, a group of lowland and a group of hill farmers were surveyed to assess whether, and to what extent, the groups' preferences differ from the experts' preferences. The part-worth utilities obtained from the surveys were converted into relative economic value terms per unit change in each trait. These measures - referred to as 'preference economic values' (pEVs) - were compared with economic values for the traits obtained from bio-economic models. The traits 'value per lamb at the meat processor' and 'lamb survival to slaughter' were revealed as being the two most important traits for the surveyed experts responding as lowland and hill farmers, respectively. In contrast, 'number of foot baths per year for ewes' and 'number of anthelmintic treatments per year for ewes' were the two least important traits. With the exception of 'carcase fat class' (P < 0.05), there were no statistically significant differences in the mean pEVs obtained from the surveyed experts under both the lowland and hill farming scenarios. Compared with the economic values obtained from bio-economic models, the pEVs for 'lambing difficulty' when the experts responded as lowland farmers were higher (P < 0.001); and they were lower (P < 0.001) for 'carcase conformation class', 'carcase fat class' (less negative) and 'ewe mature weight' (less negative) under both scenarios. Compared with surveyed experts, pEVs from lowland farmers differed significantly for 'lambing difficulty', 'lamb survival to slaughter', 'average days to slaughter of lambs', 'number of foot baths per year for ewes', 'number of anthelmintic treatments per year for ewes' and 'ewe mature weight'. Compared with surveyed experts, pEVs from hill farmers differed significantly for 'lambing difficulty', 'average days to slaughter of lambs' and 'number of foot baths per year for ewes'. This study indicates that preference-based tools have the potential to contribute to the definition of breeding objectives where production and price data are not available.