In a pilot study involving proficiency testing for human immunodeficiency virus, markedly diverse and potentially confusing test report forms were encountered among participating laboratories. Therefore, a comprehensive study of human immunodeficiency virus type 1 report forms was conducted from state-licensed testing laboratories in California. Participants analyzed three serum samples of known human immunodeficiency virus type 1 antibody reactivity and reported their results on forms that they would normally submit to clinicians. Report forms from 84 laboratories were evaluated for content, design, and clarity. Differences were found among commercial, hospital, and public health laboratories. The significance of these findings is discussed. This technique also may be applied to evaluate laboratory report form design and content for other diagnostic test results.