Due to the importance of wild oat (Avena sterilis L. subsp. ludoviciana (Durieu) Nyman y A. fatua L.) damage in Aragon (NorthEastern Spain) the main yield loss prediction models has been evaluated on irrigated wheat crops. Data were taken from a seven years trial field. Logistic models were best adapted to these conditions while simple models predicted satisfactorily only in particular infestation levels. The models efficacy showing the competition at different wild oats densities and other advantages or drawbacks are described on this paper.