This paper analyses energy demand of Port-Harcourt refinery, Nigeria, based on information obtained from its annual publications, backed-up by spot interviews. The analytical approach adopted for the study involves the calculation of energy intensities to determine the refinery's annual energy demand for various energy types considered from 1989 to 2004. The results showed that the actual energy demand per year for processing crude oil into refined products, exceeded, in varying degrees the stipulated refinery standard of 4 barrels of oil equivalent (BOE) per 100 BOE. It varied from 4.28-8.58 BOE per 100 BOE. In terms of energy demand efficiency, this implies very poor performance of the refinery during the 16-year period under investigation. The excess demand which translates to an average daily wastage of about 2005 BOE is estimated to be $56,196 (US Dollars) based on the 2003 OPEC basket price of $28.0213 per barrel. Lack of optimal fuel utilization-mix and non-compliance with the Turn-Around-Maintenance schedules were attributed to the refinery's inefficient energy demand pattern. (c) 2006 Elsevier Ltd. All rights reserved.