East Foundry Cove and Constitution Marsh are located on the east side of the Hudson River, 85 km upriver from lower Manhattan. Between 1965 and 1971, Marathon Battery Company discharged an estimated 51,004 kg of particulate cadmium, and 1569 kg of soluble cadmium were discharged directly into East Foundry Cove, which became a Superfund site in 1994. Dredging and restoration of East Foundry Cove were completed in 1996. Cadmium concentrations were reduced from greater than 900 mg/kg to less than 3 mg/kg in East Foundry Cove. Constitution Marsh and South Cove were not included in Superfund restoration. For this study, 738 surface sediment samples were collected from 15 sampling sites on 8 occasions from 18 September 1997 to 30 October 1998. Diatoms were identified and enumerated for each collected sample. These data were analyzed using Bray-Curtis similarity, MDS ordination, analysis of similarity (ANOSIM), and similarity of percentages (SIMPER). Cadmium concentrations (mg/kg) were also determined for each sample. Results show the communities of diatoms were different in two stations (1 and 3) in East Foundry Cove from the remainder of the stations in the study. However, one East Foundry Cove station (2) was more similar to the stations in South Cove and the southern stations of Constitution Marsh. Three of the most abundant taxa, Navicula gregaria, Cyclotella meneghiniana, and Cocconeis placentula var. lineata, were present in similar proportions at all sampling sites. Navicula gregaria, however, occurred in greater relative abundance at stations 4 and 5 and in Constitution Marsh, adjacent to restored East Foundry Cove, than in any other stations.