<p>In January 2013, the National Healthcare Safety Network definition of "present on admission" was created. Using existing surveillance data from 2013, we identified health care-associated infections (HAIs) that met prior present on admission criteria but not the new definition. We identified a number of infections classified as HAI despite evidence that infection was clinically present on admission. These findings have important implications for states with mandatory HAI reporting using National Healthcare Safety Network definitions.</p>