Samples of blubber, muscle, liver, and kidney of short-finned pilot whaleGlobicephala macrorhynchaand long-snouted dolphinStenella(longirostris?) from waters adjacent to St. Lucia, Lesser Antilles, were analyzed for Hg, DDT, dieldrin, and PCB. Total Hg levels were high, ranging from 1.33 to 5.36 ppm in muscle (methylated fraction 42–100%), 2.28 to 14.00 ppm in kidney (methylated fraction about 14%), and 13.00 to 157.00 ppm in liver (methylated fraction 2–17%). ΣDDT in blubber ranged from 1.25 to 7.38 ppm, dieldrin in blubber from 0.007 to 0.04 ppm, and PCB in blubber from 0.69 to 5.00 ppm. The presence of the high Hg levels is attributed largely to natural sources, as the Lesser Antilles Island Arc is a site of intense cyclic tectonic activity. There may be some contribution from atmospheric sources. Both DDT and PCB could be largely the result of atmospheric transportation from higher Atantic latitudes, although local DDT spraying programs may have contributed. Certainly the circulation pattern in the Gulf of Mexico and Caribbean appears to rule out water-borne transport from the river systems of the Gulf States of the United States.