For the solution of a large-deformation and/or buckling problem of a shell structure subjected to deformation-dependent pressure loads, methods are required that account for the effects of the change of loading direction and loaded area during its deformation. This paper presents a geometrically non-linear finite-element-analysis procedure for this type of problem, and attention is focused on a stiffness matrix known as the load-stiffness or the load-correction matrix. The load-stiffness matrix, in general, takes a non-symmetric form, which is a major disadvantage when incorporating it into existing finite-element computer programs. In this paper, an effective load-stiffness matrix with a symmetric form is presented for a general structure subjected to uniform pressure loads. A simple procedure is used to derive this load-stiffness matrix. Several numerical examples of instability problems are presented that demonstrate the validity of the proposed method.