Thermal neutron activation analysis was applied to the nondestructive determination of parts per billion (p.p.b.) quantities of mercury in high purity, oxygen-free high conductivity (OFHC) copper. The data were treated to a five-point gamma spectrum smoothing to reduce the statistical variations due to the low count rates. Linear regression and a statistical evaluation of the data were also performed. Net photopeak counting rates of approximately 43 counts per minute (c.p.m.), compared to a background of approximately 6 c.p.m., were obtained for six two-gram copper samples containing 38 ± 12 p.p.b. mercury.