Electrophysiology: The biomedical field dealing with the study of electric activity in the body. Electrophysiology includes the study of the production of electrical activity and the effects of that electrical activity on the body. See, for example: Electrophysiologic retinal testing ; and Electrophysiologic study of the heart. The procedure is performed in an electrophysiology laboratory under controlled clinical circumstances. The procedure is performed by cardiologists and nurses who specialize in electrophysiology. An EP study is generally a very safe procedure. However, as with any invasive procedure, there are risks. Special precautions are taken to decrease these risks. Please talk to your doctor about any concerns you may have about the risks and benefits of the procedure.