This paper is concerned with the exact geometrical formulation for truss buckling. Based on the assumptions of large member rotations but small strains, a generalized formulation is presented for the nonlinear analysis of trusses in their deformed state. Conditions for instability are included and the snap-through load is accurately predicted for various examples by using the Newton-Raphson approach. The formulation is used to study the response of cable networks to external loads. Under uniformly distributed loads the networks behaved linearly with very small nodal displacements. In other loading cases, where the load distribution is unsymmetrical and the total load applied is smaller than the uniform loading, very large displacements occurred with significant nonlinearities.