A self-consistent field analytical theory is developed to analyze the equilibrium structure of weakly charged polyelectrolyte brushes in salt-free solutions. In contrast to previous studies based on the local electroneutrality approximation valid for sufficiently strongly charged or densely grafted (''osmatic'') brushes, we consider a general ease comprising both limits of weakly and strongly charged systems without any a priori assumptions about the distribution of counterions. The analytical expressions for various structural properties of free and confined polyelectrolyte brushes are obtained and compared to existing scaling predictions, The elastic response and structural rearrangement in the polyelectrolyte brush under compression are analyzed. (C) 1997 American Institute of Physics.