Hi... I am graduate student at a US university. I went US in Jan 2009. I came back to india taking a leave of absence in May 2009 without completing my study due to a health problem. I am still continuting my study for fall semester from india itself through internet study and I am enrolled less than half time. I have been out of US for more than 5 months. I want to come back and US university will provide me with initial attendance I 20. My visa is still valid uptill Jan 2014. Do I need to again apply for a new visa?

If you leave US longer than 5 months, you must apply for a new F-1.