Electronic Journal of Differential Equations, Vol. 2011 (2011), No. 106, pp. 1-10. Title: Modified quasi-boundary value method for Cauchy problems of elliptic equations with variable coefficients Author: Hongwu Zhang (Lanzhou Univ., Gansu, China) Abstract: In this article, we study a Cauchy problem for an elliptic equation with variable coefficients. It is well-known that such a problem is severely ill-posed; i.e., the solution does not depend continuously on the Cauchy data. We propose a modified quasi-boundary value regularization method to solve it. Convergence estimates are established under two a priori assumptions on the exact solution. A numerical example is given to illustrate our proposed method. Submitted May 4, 2011. Published August 23, 2011. Math Subject Classifications: 35J15, 35J57, 65G20, 65T50. Key Words: Ill-posed problem; Cauchy problem; elliptic equation; quasi-boundary value method; convergence estimates.