Data are tabulated to identify all major and minor gamma-ray interferences which may effect the area determinations of analytical photopeaks for all principle isotopes (of half life greater than about one day) encountered during the routine instrumental neutron activation analysis of silicate rocks. These photopeaks cover the energy range 60–1700 keV and are based on data abstracted from ERDTMANN and SOYKA.8 Interferences are listed down to relative intensities of 0.001% and include principle sum peaks. Photopeaks which are considered to be most reliable for routine quantitative analysis are identified.