The increasing importance of the carbon sequestration issue calls the researchers to investigate if the agri-environmental support (AES) to extensive mountain grazing granted under Regulations 2078/92, 1257/99 and 1698/2005 is still efficient. AES may have contributed to the maintenance of low carbon stocks in extensive grazing areas, which might otherwise have been abandoned and revegetated by species that assist carbon sequestration. We evaluate benefits and costs of supporting the maintenance of pastureland through cattle grazing in an Italian Alpine pasture for 2004. We focus on three non-commodity outputs of Alpine grazing –landscape-recreation amenities, carbon sequestration and contribution to economic vitality of the area- and three groups of agents: visitors, local community and EU households. The efficiency of supporting mountain grazing is demonstrated by a net benefit of euro 228,613. Landscape-recreational benefits are the key variable, as their value (euro 205,377) is large enough to justify the grazing activity and the related support. The value of carbon sequestration achievable with reforestation (euro 62,491) could not compensate the loss in tourism benefits. Net beneficiaries of the agri-environmental policy are not the farmers but the visitors and the local community. Transforming of the intangible goods (both landscape-recreational amenities and carbon sequestration) into tangible ones would favour the local community. The overall convenience of supporting the maintenance of Alpine pastureland through cattle grazing depends on the number and the types of benefits and costs we consider. When a complete evaluation of all the benefit and cost flow is impossible or when an aspect, previously considered as irrelevant, suddenly increases its importance (such in the case of carbon sequestration), an approach inspired by the precautionary principle is absolutely necessary and wise.