Some results on the existence of global Chebyshev coordinates on a Riemannian two-manifold or, more generally, on an Aleksandrov surface M are proved. For instance, if the positive and the negative part of the integral curvature of M are less than 2π, then there exist global Chebyshev coordinates on M. Such coordinates help one to construct bi-Lipschitz maps between surfaces. Bibliography: 9 titles.