The shipwreck of the Amoco Cadiz supertanker on the rocks of the Brittany coast in France (March 1978) and the blowout of Ixtoc-I well in the Gulf of Mexico (June 1979) were the most important oil spills ever recorded. The crude oils discharged in the marine environment from both accidents were light petroleums and their chemical compositions were similar (Table 1). After these two oil spills we examined the hydrocarbon pollution in the marine environment. Our chemical studies were limited to an overall estimate of the oil content to assess the importance of and the extent of the pollution at the seawater surface and into the water colurmn plus the sediment contamination. The andytical techniques used were UV spectrofluorometry for the seawater samples and IR spectrophotometry for the sediment samples. The Ixtoc-I study was less important than the Amoco Cadiz one, and was limited to the analysis of samples collected during only one oceanographic cruise. [NOT CONTROLLED OCR]