The implementation of ISO 14000 certification in a company involves a set of costs and benefits that must be known in order to assess the investment effectively in terms of environmental quality. However, as will be shown, these figures can be difficult to calculate, mainly because of a lack of reference data or specific assessment criteria. Moreover, few companies have so far implemented an Environmental Management System. Investments in environment quality sometimes simply look like costs, but benefits do exist and these are often economically quantifiable. Such benefits depend on the choice and the pursuit of aims, on the respect of rules (e.g. no omissions) and on environmental efficiency (e.g. no waste), and can only be calculated following an in-depth analysis of the system. A first and approximate estimate of these costs and benefits has been obtained for a number of real industrial cases, mainly in the chemical field, and the survey results are given in this paper. The research was carried out in Italy in companies implementing an Environmental Management System in most cases in accordance with the ISO 14000 series