An analytical method was developed for monitoring environmental pollutants by using blue mussels or gray mullets as a biological indicator. The method involves extraction with acetonitrile, followed by liquid-liquid partitioning, the use of a Florisil dry column for defatting, and a final silica gel column clean-up to yield five fractions. The fractions from blue mussels or gray mullets were analyzed by using FPD-GC, FID-GC, ECD-GC, GC-MS and fluorescence spectrophotometry. Various kinds of pollutants were present in them, and clear quantitative and qualitative differences were observed among the substances from samples collected in regions of relatively clean sea and polluted sea.The results so far obtained indicate that this analytical method is applicable to a monitoring system for environmental pollutants and that blue mussels are a more appropriate biological indicator than gray mullets for monitoring various kinds of compounds in marine samples.