Requirements to take P.E. Exam

To take P.E. Exam, one has to meet requirements on

• Education Background
  
• Engineering Experience
  
• F.E. Exam
• (Residency)

Each state acts independently to set its own requirements. States can have widely different requirements in these areas.
Many engineers, who works in U.S. with a H-1B visa, have a M.S. and/or Ph.D. degree from an ABET-accredited university but a B.S. degree from universities outside U.S. They have to contact the state board in order to know how many years of engineering experience they need and what kind of experience qualifies.

The answers to the above two questions vary with personal background and state requirements.

Qualifying Experiences:

• The state bases its decision on the descriptions of your work experience that you and your references provide. Only experience wherein you have made use of your engineering knowledge will count.
• Research in graduate school can be qualifying experience. But it depends on what you did.

Years of Qualifying Experiences:

• In California it is possible to take a Principles and Practice in Engineering examination with only two years of experience after a bachelor's degree, or one year of experience after graduate school. where there is a state-specific structural engineering exam and two additional exams in land surveying and earthquake engineering for civil engineering candidates.
• In Nevada, college graduates are eligible to take the Principles and Practice exam immediately after graduation and passing the EIT, before acquiring the required experience.

References:
http://en.wikipedia.org/wiki/Professional_Engineer
http://www.ppi2pass.com/ppi/PPIInfo_pg_map-ma.html
http://www.mass.gov/Eoca/docs/dpl/boards/en/en_faq_app_guidelines.pdf
http://www.ppi2pass.com/ppi/PPIInfo_pg_myppi-faqs-examfaqs.html