Interest and concern that the shared communion cup may act as a vehicle for indirectly transmitting infectious disease was reawakened when the human immunodeficiency virus (HIV) was detected in the saliva of infected persons. Bacteriological experiments have shown that the occasional transmission of micro-organisms is unaffected by the alcoholic content of the wine, the constituent material of the cup or the practice of partially rotating it, but is appreciably reduced when a cloth is used to wipe the lip of the cup between communicants. Nevertheless, transmission does not necessarily imply inoculation or infection. Consideration of the epidemiology of micro-organisms that may be transmitted via saliva, particularly the herpes group of viruses, suggests that indirect transmission of infection is rare and in most instances a much greater opportunity exists for direct transmission by other means. There is substantial evidence that neither infection with hepatitis B virus nor HIV can be transmitted directly via saliva so that indirect transmission via inanimate objects is even less likely. No episode of disease attributable to the shared communion cup has ever been reported. Currently available data do not provide any support for suggesting that the practice of sharing a common communion cup should be abandoned because it might spread infection.