The progressive transformation of power systems driven by decarbonization policies is asking for new contributions and new actors. Multi-energy systems operating on the distribution grids and linking several energy vectors represent an ideal mean to support the transition in a reliable and fruitful way. Indeed, these systems act on multi-markets and provide high-performance services with their devices, taken as single or aggregated units. In this paper, a study is proposed regarding the efficacy and the economic impact of MES provision of ancillary services to flexibility markets. This is carried out by several simulations along different seasons, adopting the Italian regulation and balancing rules. The results show that MESs own high flexibilityavailability, but receive little economic revenue, markets show a low capacity to get this flexibility.