[en] The study is an extension of a Chesapeake Bay-wide analysis of toxic organic substances into the Elizabeth and Patapsco River subestuaries. Twenty-eight surface sediment samples from the Elizabeth River and 40 surface sediment samples from the Patapsco, were analyzed in detail for the presence of mainly aromatic and polar organic compounds. Approximately 310 distinct compounds were identified by gas chromatography-mass spectrometry in the Elizabeth River samples, and about 480 in the Patapsco. Total aromatic concentrations ranged from 440,000 to 3,100 ppb in the Elizabeth and from 2.7 x 10⁶ to 6100 ppb in the Patapsco. Similar to observation in the Chesapeake Bay, unsubstituted polynuclear aromatic hydrocarbons dominated, contributing about 50% to the total resolved concentration