Air trapped in polar ice cores is a valuable archive for determining paleoatmospheric levels of ultratrace gases that have weak emissions and are removed quickly from the atmosphere, resulting in abundances ranging from parts per billion (ppb) down to parts per trillion (ppt). Despite very low atmospheric abundances, ultra-trace gases have profound influence on the chemistry of the atmosphere and impact global climate. In this article, firn air and ice core measurements of carbon monoxide, carbonyl sulfide, ethane, acetylene, methyl chloride, and methyl bromide are reviewed and discussed.