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In the framework of an extensive investigation regarding crack initiation and propagation during low-cycle fatigue in Duplex Stainless Steels (DSS), the present study was focused on the fatigue surface damage in a low nitrogen DSS. The Coffin Manson curve is presented for DIN W Nr.1.4460 DSS and compared with that of high nitrogen steel SAF 2507. The surface damage has been observed by optical and electronic microscopy and analysed in relation to the underlying dislocation structure by transmission electron microscopy. The results for the present low nitrogen steel DIN W Nr 1.4460 show that, _ At Äåt = 0.8x10-2 (Äåp = 2.5x10-3 at midlife), the preferred site for short cracks initiation seems to be the intense slip marks formed mostly in the ferrite and less frequently at phase boundaries. On the contrary, for the high nitrogen steel SAF 2507, the preferred site for short cracks initiation seems to be the intense slip marks formed in the austenitic phase. _ At Äåt = 1.2x10-2 (Äåp = 6.5x10-3 at midlife) the microcracks form mostly at phase boundaries. _ Intense slip marks are formed frequently in the ferrite. However for high nitrogen steel SAF 2507 these marks are formed in the austenitic phase. _ Intense slip marks observed on the specimen surface are correlated with intense shear bands developed beneath the surface of the specimen. _ The most important feature of the dislocation structure developed just beneath the surface of the specimen corresponds to intense shear bands oriented in the direction of the shear plane crossing grains and phases when the K-S relation is satisfied. _ The efficiency of the coupling between phases seems to play an important role in the crack formation process. Key words: low cycle fatigue, crack nucleation, microstructures, stainless steels.