Initial yield conditions and elastic-plastic response of sintered porous iron are investigated under combined tension and torsion. By using tubular specimens of initial relative densities 0.8 - 0.9, initial yield conditions were compared with several yield functions in the literature. Kim`s yield function agreed well with experimental data from combined tension and torsion of sintered porous iron. Gurson`s and Richmond and Smelser`s yield functions did not agree well with data for initial densities lower than 0.9. Shima and Oyane`s yield function showed reasonably good agreement in tension, but not so good in torsion. Other characteristic behaviors of porous metals are also investigated.