Can I leave the U.S if my I-539 extension application is in review?I'm on B2 visa & My I-94 is expired.

Even if the I-539 extension application is in review, you should either leave the US prior to the time that you requested or file a further application for extension of stay. Leaving the US before the time expires that you requested should have no adverse consequences to your immigration nor affect your visa in the future. You should, however, remember that you are only a visitor to the US and should properly space your next trip to the country. Due to the limitations of the Lawyers.com Forums, Alan Lee, Esq.'s (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.