The environmental hazard potential of a total of 15 chemicals that are transported through the Finnish coastal areas was assessed in this paper using a scoring method developed for accidents. The study indicates that the chemicals most commonly transported/handled in Finnish ports are methanol, sodium hydroxide solution, acids, pentanes, phenol, xylenes, methyl tert-butyl ether, ethanol and ethanol solutions. For the evaluation of the environmental hazardousness of various chemicals, a priority list of chemicals that are the most commonly transported regionally in marine environments was compiled for this study. The method used has many similarities to other commonly used scoring systems, but this study gave more weight to specific characteristics of an accidental release, water biota and impact on the environment. Nonylphenol, ammonia and sulphuric acid ranked as the most hazardous substances on the list. The results of the study can be used by rescue and environmental authorities and enterprises to improve preparedness for accidents and to mitigate the effects of accidental spills.