ABSTRACT Background: Test-seeking is associated with HIV in Brazilian blood donors. This study sought to investigate the frequency with which three different donor groups: deferred donors, accepted donors who tested HIV positive [HIV (+)], and accepted donors who tested infectious disease markers negative [IDM (−)], came to the blood bank at the suggestion of a health care professional. Study design and methods: Donors deferred for reporting high-risk behaviors and participants in an HIV risk factor case-control study completed a confidential audio computer-assisted self-interview (ACASI) that included two questions related to health care professionals and test-seeking. Results: Of 4013 enrolled deferred donors, 468 (11.8%) reported a health care professional suggested donation as a way to be tested for infection. Of 341 HIV (+) and 791 IDM (−) participants, 43 (12.6%) and 11 (1.4%), respectively, reported a health care professional suggested donation as a way to be tested for infection. Physicians were the most frequently reported source of referral: [(61.5% of deferred, 69.1% of HIV (+), and 9.1% of IDM (−) donors)]. Conclusion: HIV (+) donors and deferred donors were 10 times more likely to report test-seeking behavior by suggestion of health care professional than IDM (−) donors. If true, efforts should be made to educate health care professionals and blood donors on how to safeguard the blood supply, emphasizing that HIV testing should be done at volunteer testing centers rather than at the blood centers.