Oil refineries are one of the greatest type of industrial plant which can lead to emission of VOC and sulphur compounds. Such emissions often originate a problem of odour pollution in the human settlements located around the refinery. In many cases, odour nuisances lead the local authorities to intervene, sometimes by closing the whole plant. Odour emissions in refineries typically arise from the operating process: the aim of this work is to propose a method for the evaluation of the Odour Emission Rates from the different sources of a refinery. More in detail, the proposed method aims to quantify the Odour Emission Rate from the fugitive emissions relevant to storage tanks, whose evaluation is very complex due to the difficulty of determining both a representative odour concentration and an emitted air flow representative of this kind of sources. This method first quantifies the mass emission from the tanks, by means of the software US EPA TANKS 4.09, and after the so called “Hydrocarbon Odour Emission Capacity”, associated with different hydrocarbons mixtures. By coupling this information, it is finally possible to give an estimate of the Odour Emission Rate deriving from a storage tank and use it in an atmospheric dispersion model.