Belgium's Maritime Zone of Interest (BMZI), including the Belgian Territorial Sea, Belgian Continental Shelf, and Bonn Agreement Zone of Multilateral Responsibility, were regularly surveyed by remote-sensing aircraft for the presence of operational oil spills between 1991 and 1995, Simultaneously wind speed and direction were recorded; wave height was obtained from the literature, In total, 228 spills of various sizes, volumes and origins mere analysed by means of univariate statistical analysis. We documented that the observed oil spills were generally elongate, narrow and thin, that spill dimensions were interrelated, and that wind speed and wave height affected these dimensions. A major fraction of the total variation however could be attributed to slick thickness. Spills found outside the Traffic Separation Scheme (TSS) tended to be smaller in surface area but showed no significant difference in average volume. Thus, the source of the spill more so than the hydrodynamics of the sea determined the characteristics of the spill. Given the impact of oil spills on marine life, continuous attention should be paid to monitoring and pollution control measures in the BMZI, (C) 2000 Elsevier Science Ltd. All rights reserved.