OBJECTIVE: Evaluate a computer-assisted telephone counseling (CATC) decision aid for men considering a prostate specific antigen (PSA) test. METHODS: Eligible men were invited by their primary care providers (PCPs) to participate. Those consenting received an educational booklet followed by CATC. The counselor assessed stage of readiness, reviewed booklet information, corrected knowledge deficits and helped with a values clarification exercise. The materials presented advantages and disadvantages of being screened and did not advocate for testing or for not testing. Outcome measures included changes in stage, decisional conflict, decisional satisfaction, perceived vulnerability and congruence of a PSA testing decision with a pros/cons score. Baseline and final surveys were administered by telephone. RESULTS: There was an increase in PSA knowledge (p CONCLUSIONS: The intervention provides realistic, unbiased and effective decision support for men facing a difficult and confusing decision. PRACTICE IMPLICATIONS: Our intervention could potentially replace a discussion of PSA testing with the PCP for most men.