Spirometry is an essential part of diagnosing a child with asthma. The National Asthma Education and Prevention Program (NAEPP) and the Global Initiative for Asthma (GINA) expert panels recommend spirometry to be performed on children five years of age and older as an objective assessment of lung function, to diagnosis asthma, and for ongoing yearly management of asthma (GINA, 2012; NAEPP, 2007). According to the NAEPP expert panel, history and physical examination alone are not reliable to accurately diagnose asthma, exclude alternative diagnosis, or determine lung impairment (NAEPP, 2007). Dombkowski, Hassan, Wasilevich, and Clark (2010) found 52% of physicians who provide primary care to children used spirometry, but only 21% used spirometry according to the national guidelines, and only 35% of physicians surveyed were comfortable interpreting the test results. Zanconato, Meneghelli, Braga, Zacchello, and Baraldi (2005) found that 21% of spirometry readings were interpreted incorrectly, concluding that proper training and quality control were important to provide if spirometry in the primary care office setting is to be used. The purpose of this article is to review the appropriate use of spirometry in pediatric primary care.