The article first provides two examples of a physician's treatment of patients with communicable diseases who may remain infectious to other people. It then discusses precedent in tort law regarding physicians' liability to nonpatients for the treatment and subsequent conduct of patients. The concluding section describes recommendations for physician conduct and for a legal standard regarding physician liability to nonpatients. The article concludes that the spread of a communicable disease presents a serious threat of litigation against the physician who treats the patient with that disease. It urges public health departments and physicians to adopt procedures limiting their potential liability and raising safeguards for the public health, including close supervision of TB victims who fail to comply with prescribed treatments and individual warnings to identifiable people who risk contracting TB or AIDS. The article further suggests that courts limit physicians' liability to newly infected people, possibly by making clear that concerns about patients' rights (including confidentiality) dictate against certain potential safeguards for nonpatients. 110 footnotes.