Seaports provide multiple services to ships, cargo, and passengers. These services can be performed by a combination of public and private initiatives and usually the role of public sector institutions is to regulate and supervise private firms. Cargo handling varies according to the type of goods involved. In performing that task public sector institutions need to know firms¿ cost structure deeply, so they can regulate them appropiately. This paper argues that the operation of port terminals must be analysed by means of multiproduct theory. This allows the calculation of several cost indicators (economies of scale, scope, and so forth) which are key tools to help regulators¿ job. Finally, a literature review about ports¿ cost structure is ...