We reviewed some moral hazard (MH) models applied to agri-environmental policies and identified the main methodological aspects of the literature on this topics. Imperfect vs incomplete monitoring , static vs dynamic and single vs multiple agents models are the main lines along which the literature has been organised analysing each component of a MH model. Most papers point out the role of farmers' risk aversion in mitigating MH. Others highlight that the observed high rate of compliance is still somewhat paradoxical given current enforcement strategies with low fines and monitoring levels. Cross compliance confirm these findings and urges further studies on dynamic models and farmers' non profit maximising behaviour.