In a series of studies aimed at investigating the role of environmental surfaces in the transmission of certain respiratory virus infections, it was shown that small amounts of nasal mucus containing rhinovirus (infectious mucus) can spread from fingertips to door knobs, faucet handles, or other environmental surfaces and remain infectious for many hours. These surfaces can serve as a reservoir of virus and may provide sufficient infectious material to contaminate hands. Recent studies have shown that once virus is on the fingers, it may be transferred to the nasal and conjunctival mucosa by means of autoinoculation. It has been estimated that as little as 1.0 plaque-forming unit can produce an infection in a susceptible human. In the present experiments, the amount of rhinovirus transmitted from fingers contaminated with infectious mucus to environmental surfaces and from there onto the fingers of a volunteer who touched the contaminated objects was quantitated, and the efficiency of transfer was studied. From 3 to 1,800 plaque-forming units of rhinovirus were recovered from the fingertips of volunteers (recipients) who handled either a door knob or a faucet that had previously been manipulated by another volunteer (donor) whose fingers were contaminated with infectious mucus. The average amount of rhinovirus recovered from the fingers of the recipients was approximately 13.5% of the amount recoverable from the fingers of the donor. In experiments in which there was direct hand-to-hand contact between donor and recipient, about 6.7% of the virus present on the fingertips of donors was recoverable from the recipients.