Do highschool grades matter?

[hectic]

Seriously?

I had no chance there anyway. 

[bruin]

I doubt they plays any role in admission. The whole point of the SAT/ACT is to predict college performance/aptitude, which is measured by your GPA. I think they may use these scores to see your standardized test history, whether you do excepionally well/badly.

[HippieLawChick]

They don't matter at all.  The only school that even asked about them (that I applied to) was Harvard. 

I doubt they care about my big 29 on the ACT or my terrific high school grades

[bruin]

I don't recall having to put that on my Harvard app.