This paper describes the Environmental Sensitivity Index (ESI) for oil-spill accidents for the Santa Catarina Island and surrounded areas. The shoreline classification was obtained according to the Guidelines for ESI elaboration, established by the Environmental Quality Secretariat of the Environmental Ministry (SQA/MMA, 2002). Field works and literature review were conduced in order to fulfill all the required information for the classification. All information was processed by a geographic information software system, Arc Map 8.3. The study area was divided into 291 segments, resulting in 447,5 km of shoreline classification. Index 10 is the most frequent in the study area, representing about 36% (mangroves, salt marshes and vegetated river-margins). The index 7 was not determined in the study area. The resulting ESI maps are articulated in 7 Operational Maps at 1:50.000 scales.