Sharp waves can be a normal or abnormal finding depending on the age and state of the neonatal patient. Sharp waves are also suspected to be abnormal based on their location, frequency, duration, and asymmetry. Inter-reader agreement does not always occur. Abnormal sharp waves may be an indication of an underlying focal region of irritability or epileptogenicity. Following anti-epileptic medication administration, localized sharp waves may be present in that region of seizure origin. This chapter will present guidelines for determining normal and abnormal sharp waves. This chapter is based on Hrachovy et al. [3], Lobroso [4], Mizrahi and Hrachovy [5], Sansavere and Harrar [6].