The Virginia legislature approved chemical tests in 1954. Chemical testing for intoxication became possible when scientists recognized that the amount of alcohol in the brain could be measured to determine the level of intoxication. Although experts disagree concerning the accuracy of breath testing, it has become recognized widely in criminal proceedings. The major significance of the use of breath testing in drunken driving prosecutions lies in the statutory presumption of intoxication that results from a breathalyzer reading above a certain level. At least 28 States, including Virginia, have established the intoxication level at 0.10 percent or higher. Statutory presumptions of intoxication derived from breathalyzer test results are rebuttable rather than conclusive. Challenges to the admissibility of a breathalyzer test, which result when the ampoules containing the breath sample are unavailable for independent analysis by the defendant, are based on denial of the defendant's due process rights. The basis for such challenges is found in the Supreme Court's ruling in Brady v. Maryland (1963). Despite challenges raised in other State courts, it is predicted that the Virginia courts will adopt the position that destruction of used breathalyzer test ampoules does not interfere with the defendant's ability to determine the facts or raise a defense. This note asserts that the spirit of due process is served best by requiring the prosecution to retain the breathalyzer ampoule for the defendant's independent analysis or suffer the sanction of the suppression of breath test results. Legislation on the question or retention of breathalyzer ampoules would serve both defendants and the prosecution. Until such legislative action is taken, the best protection for the defendant faced with breathalyzer test results but no ampoule to impeach those results is to present expert testimony during trial as to the fallibility of the test. In addition, defense counsel must request strong jury instruction to counteract the prejudice attendant in breathalyzer evidence. The note provides 249 footnotes.