Livers of 42 pintail hens (Anas acuta) breeding in eastern North Dakota during the spring and early summer of 1969 and 1970 were analyzed for total mercury by the neutron activation technique. Mercury content on a wet weight basis ranged from 0.055 ppm to 9.512 ppm and averaged 0.888 i?? 1.796 ppm (SD). Liver mercury levels of hens collected in early spring (prior to planting of crops) were significantly lower than those of hens taken late in the nesting season (P < 0.01). Mercury residues among prelaying, laying, and postlaying groups collected following the onset of spring planting did not differ significantly (P > 0.05). Albumen mercury residue was correlated with liver mercury content (r = 0.756, P < 0.05). Mercury content in livers of five wild juveniles averaged 0.123 i?? 0.074 ppm.