The article is dedicated to the analysis of the methods of mortgage loan repayment modeling. The issues examined: base elements of a mortgage loan, interrelation of these elements and their influence on the value of payment and the total amount of the interest paid for a loan. The two most widely spread in Russia methods of mortgage loan repayment modeling are represented: annuity payments and variable (reducing) payments. The mathematical formulas deducted for calculating principal and interest payments in both methods. Special attention is paid to the issue of partial principal prepayment, its' influence on the structure and the amount of payment in the annuity payments method. The issues analyzed could be applied in the development of mortgage lending programs within credit organizations, and also could benefit to individual borrowers while choosing the optimal terms of a mortgage loan.