PMID and PMCID are not the same thing.
PMID is the unique identifier number used in PubMed. They are assigned to each article record when it enters the PubMed system, so an in press publication will not have one unless it is issued as an electronic pre-pub. The PMID# is always found at the end of a PubMed citation.
Example of PMID#: Diehl SJ. Incorporating health literacy into adult basic education: from life skills to life saving. N C Med J. 2007 Sep-Oct;68(5):336-9. Review. PubMed PMID: 18183754.
PMCID is the unique identifier number used in PubMed Central. People are usually looking for this number in order to comply with the NIH Public Access Regulations. We have a webpage that gathers information to guide compliance. You can find it here: http://guides.hsl.unc.edu/NIHPublicAccess
A PMCID# is assigned after an author manuscript is deposited into PubMed Central. Some journals will deposit for you. Is this your publication? What is the journal?
PMCID#s can be found at the bottom of an article citation in PubMed, but only for articles that have been deposited in PubMed Central.
Example of a PMCID#: Ishikawa H, Kiuchi T. Health literacy and health communication. Biopsychosoc Med. 2010 Nov 5;4:18. PubMed PMID: 21054840; PubMed Central PMCID: PMC2990724.