We give necessary and sufficient conditions for the convergence with geometric rate of the denominators of linear Pade-orthogonal approximants corresponding to a measure supported on a general compact set in the complex plane. Thereby, we obtain an a
nalogue of Gonchars theorem on row sequences of Pade approximants.
Starting from the orthogonal polynomial expansion of a function $F$ corresponding to a finite positive Borel measure with infinite compact support, we study the asymptotic behavior of certain associated rational functions (Pad{e}-orthogonal approxima
nts). We obtain both direct and inverse results relating the convergence of the poles of the approximants and the singularities of $F.$ Thereby, we obtain analogues of the theorems of E. Fabry, R. de Montessus de Ballore, V.I. Buslaev, and S.P. Suetin.
