An F-1 student who has attended an SEVP-certified college, university, 

conservatory, or seminary on a full-time basis for at least one academic 

year may be authorized for up to 12 months of OPT per education level. 

However, F-1 students who have one year or more of full-time curricular 

practical training are not eligible for OPT for that degree. 

Visit this link  http://www.ice.gov/doclib/sevis/pdf/opt_policy_guidance_042010.pdf 

Hope this helps.