Pandemic influenza (pH1N1) was the first health condition targeted for surveillance in 2009. Through an iterative process, a combination of ICD-9 codes and measured fever at the time of visit yielded the highest sensitivity and specificity using the case definition for influenza-like illness (ILI) found in the Centers for Disease Control and Prevention's (CDC) ILInet surveillance system. Formal evaluation of ILI surveillance using review of local medical records (electronic and paper) in one region of the country found that the system had a sensitivity of 96.4% and specificity of 97.8%. IHS is expanding EHR surveillance to capture cases of chlamydia, syphilis, HIV, invasive pneumococcal disease, measles, Haemophilus influenza type b (Hib), meningococcal disease, hepatitis B, hepatitis C and tuberculosis.