Abstract. Consider an absolutely continuous measure on a system of Jordan arcs and (closed) curves in the complex plane, assuming that this measure satisfies the Szegő condition on its support and that the support of the measure is the boundary of some (multiply connected) domain Ω containing infinity. Adding to the measure a finite number of discrete masses lying in Ω (off the support of the measure), we study the strong asymptotics of the polynomials orthogonal with respect to the perturbed measure. For this, we solve an extremal problem in a certain class of multivalued functions. Our goal is to give an explicit expression for the strong asymptotics on the support of the perturbed measure, as well as on the domain Ω. §1. IntroductionLet σ be a positive measure with compact support in the complex plane. We introduce the sequence of polynomials Q n (z) = z n + · · · orthogonal with respect to the measure σ:A fundamental problem of the theory of orthogonal polynomials is the study of their asymptotic behavior as n → ∞.As usual, by the weak asymptotics of orthogonal polynomials we mean the asymptotics of |Q n (z; σ)| 1/n . The weak asymptotics is closely related to the distribution of zeros of Q n (z) and is determined by the support of the measure σ and by the regularity properties of σ on its support. The main tool of the investigation in this case is the logarithmic potential theory [20].The ratio asymptotics is that of the ratio Q n+1 (z; σ)/Q n (z; σ). This aspect has attracted a lot of attention recently. The main progress was due to the varying weight approach, developed be G. Lopez Lagomasino and his collaborators [9]. On an interval of the real line, the ratio asymptotics of the orthogonal polynomials can be exhibited under various conditions, of which the best by now is due to Rakhmanov : σ > 0 almost everywhere on the interval.The strong asymptotics problem is the problem of uniform asymptotic behavior of the polynomials Q n (z) outside of the support of the measure and on this support. In the classical case where supp(σ) = [−1, 1], the strong asymptotics of orthogonal polynomials was investigated by S. N. Bernstein and G. Szegő [19]. The Bernstein-Szegő theory was extended to the case of the measure supported on a finite system of complex arcs 2000 Mathematics Subject Classification. Primary 42C05; Secondary 30D55, 30E15.