Patients undergoing hemodialysis for chronic renal failure develop infections with herpes simples virus (HSV) and cytomegalovirus (CMV). Therefore, body fluids of these patients and dialysis unit employees will be cultured monthly and at the time of acute illnesses to determine the relationship of infection with these viruses to the development of illness. Furthermore, measurements of humoral and cell mediated immunity to CMV and HSV in infected and uninfected patients contrasted to dialysis employees will help assess host factors in the control of infection. Additionally, isolates will be typed to determine whether disease is more prevalent in association with a particular type of CMV or HSV.