Thanks for your post!
Generally speaking, high school-era achievements should be left off your resume for b-school. The reason for this is because the schools are often skeptical of applicants who seem to be replying on accomplishments from long ago to bolster their candidacy. Simply put, they wonder if the fact that you've got high school-era accomplishments listed means that you haven't done anything of merit more recently.
Of course, there can always be exceptions to the rule - especially when it comes to younger applicants or truly substantial high school-era achivements. In your case, I'd need to know more about the examination you are referring to. Was this an entrance examination for university? If so, you might be able to list it as a bullet point under your education section (within the ugrad institution you ultimately attended). If it was merely a standardized test used to measure high school level aptitude (without any college admissions ramifications), I'm not sure it's going to be appropriate to include. In addition, if you graduated from high school more than 10 years ago, I'd think twice before prominently featuring this sort of thing.
Best of luck,
Graham
