In recent years it has become increasingly evident that viral hepatitis type B is a major disease problem among patients and/or health professionals associated with environments such as hemodialysis centers, dental operatories, clinical laboratories, and institutions for the mentally retarded. Studies have incriminated the intramural environment as well as specialized equipment and procedures as important factors in disease transmission. With hepatitis B surface antigen (HBsAg) as a marker of potentially infectious blood or body fluids such as saliva, it is possible to assess the environmental role in transmission of hepatitis B by use of a swab-rinse technique coupled with radioimmune assay. Assay procedures have been developed and utilized for detecting HBsAg on surfaces and in air and for quantitating of HBsAg in thermal and chemical inactivation studies. Specific decontamination strategies and recommendations for sterilization or disinfection procedures are described.