Bernoulli and Euler polynomials are considered for large values of the order. Convergent expansions are obtained for Bn(nz + 1/2) and En(nz + 1/2) in powers of n-1 , and coefficients are rational functions of z and hyperbolic functions of argument l/(2z). These expansions are uniformly valid for lz ± i/27TI > l/27T and lz ± i/7TI > l/7T, respectively. For a real argument, the accuracy of these approximations is restricted to the monotonic region. The range of validity of the uniformity parameter z is enlarged, respectively, to regions of the form lz ± i/2(m + 1)7TI > 1/2(m + l)?T and lz ± i/(2m + 1)7TI > 1/(2m + l)?T, m = 1, 2, 3, ... , by adding certain combinations of incomplete gamma functions to these uniform expansions. In addition, the convergence of these improved expansions is stronger, and for a real argument, the accuracy of these improved approximations is also better in the oscillatory region.