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Duplex stainless steels (DSSs) fatigue crack propagation resistance isstrongly affected both by microstructure and environment. In this work, environmentinfluence on the fatigue crack propagation in a rolled 25 Cr 7 Ni superduplex stainlesssteel was investigated considering three different stress ratios (R = Kmin/Kmax = 0.1, 0.5,0.75). Tests were performed according to ASTM E 647 standard, both in air and underhydrogen charging conditions (0.1M H2SO4 + 0.01 M KSCN aqueous solution, -0.9V/SCE). Crack fracture surfaces were extensively analysed by means of a scanningelectron microscope. Furthermore, crack paths were investigated by means of a crackprofile analysis. Nickel coated fracture surface sections obtained for constant ΔKvalues were considered in order to analyse the loading condition influence (R valuesand environment) on fatigue crack paths.