The determination of the stress state in backfilled stopes is an important step for assessing the behaviour of mine openings and for designing barricades. Most previous analyses have considered only the 2D case (plane strain condition) and neglected the effect of pore water pressure. In this paper, a three-dimensional solution is proposed for totally or partly submerged backfill. The new solution gives the normal stresses along the vertical and horizontal axes, with the effect of a surface load on the backfill. The solution is validated using laboratory experimental results taken from the literature. The good agreement obtained between the proposed analytical solution and laboratory test results indicates that this new solution provides a realistic evaluation for both the total and effective stresses in vertical backfilled stopes.