If you have good to great GRE scores, some relevant research experience (particularly important in sciences and social sciences) and strong letters of recommendation from professors, ideally who have supervised you in relevant research you may be ok.

By the time you apply you can't change much about your record. What you can control is a personal statement if the application requires one, and I've always advised students to deal with their early academic problems there. Just get in and get out. "I had a couple of bad semesters because I was young and immature -- hadn't found an intellectual passion yet, was having personal problems which now thankfully are well behind me., etc." You're not looking for sympathy (and won't get any) but you have a right to offer an explanation (not an excuse exactly) for what will be obvious from your record. One sentence or at the most two and work the explanation into a context that shows you've learned, grown, have become passionate, whatever. Not a stand alone sentence but one that fits in nicely to the rest of the document.

As someone who has written approximately 10000 letters of recommendation (or so it seems), I have on occasion provided an explanation for a student's seeming shortcomings. I always wrote honest letters, warts and accolades both, and I was always willing to explain why I thought a student's warts were minor or were not so bad in context -- if, of course, I felt that I could write a sensible explanation and that the earlier failures were not diagnostic about future performance .

Sometimes students ask for letters based on god knows what "I had you freshman year in a class of 200 students and you probably don't remember me but I got an A in your course..." In such cases I usually declined to write the letter or at least advised the student that my letter would be fairly meaningless. Ditto if I thought the student was weak and that my letter would be fairly negative. There are times for honesty, and this is one of them. I always tried to keep in mind that I had seen only part of a given students skill set, and I felt an obligation to tell him/her that I couldn't write a letter than would help although others might. And by the way you have every right, in my opinion, to ask whether the professor will be able to write a helpful letter. You're not entitled to ask about specifics, but it's a perfectly reasonable question. Just, "Do you think you could write a letter than will help me get into X." And if the professor who is writing the letter knows you well, she/he probably already has some inkling about your uneven record. In such cases, you can, at least in my opinion, ask if the professor would be willing to address that issue in the letter. Some might say no, but it's worth a try. Such a letter ought not come from a professor who doesn't know you well and can't speak with considerable authority to your present strengths.

Answered by : David Schneider, Retired Professor of Psychology
Source: http://www.quora.com/If-I-contact-a-pro ... barrassing