An analytical method using isotope dilution cold vapor inductively coupled plasma mass spectrometry (ID-CV-ICPMS) was developed for the determination of total mercury in the eggs of seabirds. Components including error magnification, verification of method accuracy and assignment of analytical uncertainty are presented in the context of collecting mercury data for single sample aliquots. Forty-one egg samples collected from common murre (Uria aalge) colonies on Little Diomede and Saint George Islands in the Bering Sea and East Amatuli and Saint Lazaria Islands in the Gulf of Alaska yielded mercury mass fraction values ranging from approximately 0.010 µg g⁻¹ to 0.360 µg g⁻¹. Relative expanded uncertainties for the individual determinations ranged from 1.2% to 4.4%. A one-way analysis of variance including pairwise comparisons across the colonies showed that mercury levels in eggs collected from the Gulf of Alaska colonies were significantly higher than their counterparts in the Bering Sea. Mercury data from each colony were normally distributed, suggesting a ubiquitous regional deposition of mercury and corresponding incorporation into local foodwebs.