There are arguments both for and against requiring the identification of test subjects under voluntary screening for AIDS virus antibodies. Only if those tested are identified can they be contacted for followup to obtain new information, gather epidemiological data, and pursue contact tracing. Many fear, however, that test results may be used to stigmatize and discriminate against those who test positive for the antibodies. One resolution of the issue might be Federal legislation to ensure confidentiality. Mandatory testing for both low-risk and high-risk groups should not be used, since it surely will involve serious coercion and invasions of privacy. The high cost of testing and the risk of false positives also argue against mandatory testing. Quarantines of the size that would be required would be unjust, costly, and impractical; and the benefits of mandatory reporting and contact tracing do not appear significant enough to justify the risks of loss of privacy and the potential for discrimination. 26 notes.