The concentrations of polycyclic and nitro musks were determined in freshwater fish from two urbanized areas in the lower Great Lakes: Hamilton Harbour in western Lake Ontario, and the Detroit River and nearby western Lake Erie. Fish collected included brown bullhead (Ameiurus nebulosus), gizzard shad (Dorosoma cepedianum), white perch (Morone americana), yellow perch (Perca fluviatilus), and a single walleye (Stizostedion vitreum). No residues of nitro musks were detected in any of the fish, but since no attempt was made to analyze for the amino-metabolites of these compounds, it cannot be ruled out that these metabolites were present in the fish tissues. Fish from Hamilton Harbour had higher concentrations of polycyclic musks in their tissues than fish from the Detroit River, with a single yellow perch from Hamilton Harbour having the highest concentration of total polycyclic musks of 945 ng/g wet weight. The three polycyclic musk compounds present in the highest concentrations in fish were, in order of relative concentration, Galaxolide® (i.e, HHCB) > Tonalide® (i.e., AHTN) > Traseolide® (i.e., ATII). Lower concentrations of Celestolide® (i.e., ADBI) and Phantolide® (i.e., AHMI) were also detected. There appeared to be species-dependent variability in the accumulation of musks that may be related to differences in the capacity of fish to metabolize these compounds.