As a mortgage underwriter and loan officer I can tell you that FNMA and FHLMC will both lend to a 644 fico (the middle of 3 scores) what will happen is that your rate will be higher because of your low score, but you won't be disqualified just because of your score. You will have to show the ability to pay and your debt ratios will be maxxed out at 45-50%, depending on what type of home you are buying. If you are looking to buy an investment property, then you'll need 15% down for a 1-unit home and 25% down for a 2-4 unit home. You will also need reserves after the closing, typically at last 6 months of reserves, so count your dollars to make sure you have enough funds for all of it. What could happen also is that if your rate and points become too high you will fall into the HCML, or high cost mortgage loan area, normally called Section 32/25 and then you'll have difficulty getting financed. That typically happened on small loan amounts because of the fees and points on an investment property. If you are buying a primary home you may want to consider FHA. You'll have pmi but your rate could be lower than conventional. Good luck