Abstract: A field study was conducted in southern Tunisia to determine the effect of irrigation regimes with saline water (3.25 dS m-1) on soil salinity, yield and water use efficiency of potato (Solanum tuberosum L., cv. Spunta) grown during autumn, winter and spring seasons. Irrigation treatments consisted in water replacements of accumulated crop evapotranspiration (ETc) at levels of 100% (100 L) 80% (80 L) 60% (60 L) and 40% (40 L), when the readily available water in the control treatment (100 L) is depleted. A daily irrigation regime at 100% of ETc (100 D) was also used. Results show that salinity was lowest under emitters and highest midway to the margin of wetted bands. Under emitters it increased gradually between 100 and 40 L from 1.0 to 2.3 dS m-1 in autumn, from 0.65 to 1.97 dS m-1 in winter and from 0.75 to 2.55 dS m-1 in spring. Highest ECe values were found to occur at about 20 and 10 cm from emitters, respectively for 100 and 40 L. Yields were highest under 100 L although no significant differences were observed with 100 D. From values of 30.4, 22.7 and 39.6 t ha-1, respectively for autumn winter and spring, yields decreased almost linearly when applied water was reduced. However, reduction in quality was significantly important for 60 and 40 L. The analysis outcome of the crop sensitivity to salt indicated, respectively for autumn, winter and spring seasons that thresholds are close to the value calculated from published salt tolerance data (1.9, 1.55, 1.85 vs. 1.7 dS m-1) but the slopes are considerably steeper (34, 54, 47 vs. 12%), apparently because of the combined effect of salinity and water stresses. Water Use Efficiency (WUE) reflected differences between seasons, it varied typically around 8-9, 6-8 and 11-14 kg m-3, respectively for autumn, winter and spring. Full irrigation with daily application resulted in the lowest WUE values, most likely because of higher evaporative losses.