Benzalkonium chloride, a quaternary ammonium compound marketed under the trade name Zephiran (Winthrop-Breon, New York, New York) was noted to be in use as a general skin disinfectant in the pain clinic. It specifically had been chosen for skin disinfection prior to nerve root blocks because the iodinated skin disinfectants have theoretic risks of neurolysis. None of the pain clinic physicians knew of the infectious risks associated with Zephiran antiseptic use. The hospital pharmacy records then were reviewed to determine where else Zephiran was being used in the medical center. Eleven different clinics and operating rooms were receiving this product in 8-ounce multi-use bottles of either tincture of Zephiran or aqueous Zephiran. There have been no infections reported from these medical service areas. However, many of the services are outpatient, and resulting infections would probably be sporadic and not easily traced to Zephiran use. This country-wide survey was undertaken to assess the present use of quaternary ammonium compounds as skin disinfectants or as compounds for environmental and equipment disinfection.