The paper is based on the analysis of a long-term mass (carbon dioxide, water vapour) and energy (solar radiation) balance monitoring programme carried out during years 2010 and 2012 in an irrigated orange orchard in Sicily, using micrometeorological methods. Orange (Citrus sinensis L.) is one of the main fruit crops worldwide and its evergreen nature may result in a great potential for carbon sequestration, but few data are currently available. In the study, the role of the orchard system in sequestering atmospheric CO2 was analyzed, thus contributing to assess the carbon balance of the specie in the specific environment. In the study, the net ecosystem exchange, the ecosystem respiration and the gross primary productivity were computed through eddy covariance (EC) method. The annual carbon uptake of the orange orchard under study was of about 6.5 t(C) ha-1 year-1 during the monitoring periods, assessing the sink capacity of the crop system. Vertical energy fluxes of net radiation, soil heat, sensible heat and latent heat fluxes were measured at orchard scale by EC. Evapotranspiration (ET) values were compared with up-scaled transpiration data determined by the sap flow heat pulse technique, evidencing the degree of correspondence between instantaneous transpirational flux at tree level and the micrometeorological measurement of ET at orchard level. Keywords: carbon balance, eddy covariance, orange orchard.