As mentioned below, currently MI expires in five years and when loan to value drops to 78%
Effective June 3, 2013 MI Will No Longer Expire!
Just in case you or another reader of your post obtained the home via an FHA loan:
FHA loans are quite different in this respect. With FHA you will have to pay Mortgage Insurance for a MINIMUM of 5 years, and until you have paid your original LOAN AMOUNT down to 78% (not that the loan amount is 80% of current market value, which is typical for non-FHA MI removal). For all but 15-year term mortgages, you will pay MI premiums for the GREATER of five years or until the amortized loan-to-value reaches 78 percent. This "78% or 5-year Rule" before Mortgage insurance can be terminated is covered here: http://www.hud.gov/offices/adm/hudclips/letters/mortgagee/fi