To determine trends in a number of hemodialysis associated diseases and practices, the Centers for Disease Control and Prevention, in collaboration with the Health Care Financing Administration, performed a mail survey of 2,304 chronic hemodialysis centers in the United States in 1993. By the end of 1993, at least three doses of hepatitis B vaccine were administered to 29% of patients and 76% of staff at responding centers. Hepatitis B surface antigen was present at low frequency in patients (incidence = 0.1%, prevalence = 1.2%) and staff members (incidence = 0.2%, prevalence = 0.3%). The 1993 incidence of hepatitis B virus infection among patients was higher at centers that accepted hepatitis B surface antigen positive patients but did not use a separate room and dialysis machine for treatment of these patients, government and profit (versus nonprofit) centers, and centers in four End Stage Renal Disease Networks. The prevalence of antibody to hepatitis C virus was 9.7% among patients and 1.6% among staff members. Pyrogenic reactions in the absence of septicemia were reported by 21% of centers and associated with use of high flux dialysis. Human immunodeficiency virus infection was known to be present in 1.5% of patients; 34% of centers reported providing hemodialysis to one or more human immunodeficiency virus infected patients.