It depends on your over-all educational picture. Many schools require that you take at least a years worth of college-level courses at a US educational institute before applying. According to the Albert Einstein web page 1 year = about 30 credits. Albert Einstein for instance also states that these credits must be in the sciences, though many schools do not state this. If you have done this then likely whether you took the pre-reqs abroad or not would not be an issue.
If your degree is from a country like Australia, Britain, New Zealand, Canada there will be no issue.
If your degree was a science degree abroad, schools look more favorably on this than if you have just the pre-reqs as they feel more certain you will have covered the 'pre-req' courses at the level required.
If you have any kind of advanced degree, even if this too was from abroad, they will be less fussy about your pre-reqs.
If you have worked in an academic lab in the states they care less about the pre-reqs.
So...as you can see, there are a lot of factors, and it will vary by school. I doubt you will get a straight answer calling schools as often you will reach the secretary rather than the dean of admissions, and at some schools only the whole admissions committee can vote to waive or accept requirements. Some schools eg U Miami state that they will not accept *any* foreign class work, let alone the pre-reqs.
What education have you received in the US? Any? If so it will improve your chances as it gives them another 'reference' level to judge your current course work on.