This volume contains a selection of invited lectures and contributed papers which were delivered at the Sixth International Conference on Navier-Stokes Equations and Related Nonlinear Problems, held in Palanga, Lithuania, 22-29 May 1997. While the emphasis was on the mathematical foundation of fluid dynamics, related contributions on nonlinear and numerical analysis were discussed as well. The topics covered incompressible fluids described by Navier-Stokes equations, compressible fluids, non-Newtonian fluids, free boundary problems, equations from thermo- and magnetohydrodynamcis, asymptotic analysis, stability, and related problems of nonlinear and numerical analysis.