The HaHB4 gene encodes a transcription factor that confers drought tolerance to Arabidopsis. Recently, we showed that wheat cultivar Cadenza expressing this gene (cv. IND-OO412-7) out-yielded the wild type (Cadenza) by 6% average, when sown in 37 field trails within the Argentine Pampas. As Cadenza is not well adapted to this region (anthesis is one month later than commercial sown cultivars), it was necessary to test the HaHB4 impact in our modern adapted cultivars. Algarrobo is an intermediate-late cultivar well adapted to our growing conditions and highly sown by farmers. Algarrobo was crossed to IND-OO412-7, and the F1 was backcrossed to Algarrobo twice to obtain the BC2. In BC1, 480 SNPs were used to help recover Algarrobo background. After the first self-pollination of BC2 (BC2S1), phenotypic selection for recurrent parent was performed during four generations, finally obtaining the AG-HB4.25 cultivar. When both cultivars were tested in different sowing dates for two years, the life cycle was very similar between them. AG-HB4.25 was slightly earlier than Algarrobo, reaching anthesis from 3 to 5 days before, depending on year and sowing date. Algarrobo and AG-HB4.25 were subsequently evaluated under two water regimes (WW: well-watered; WD: water-deficit) imposed during tillering in greenhouse conditions. Crops were grown in 1.2 m3 containers, under natural daylength and incoming radiation of the season, maximum temperature of 25°C and 160 mm (WW) or 100 mm (WD) of total soil water (1.2 m depth). Water in the soil was measured twice weekly using a Diviner 2000 probe (Sentek Pty Ltd, Australia). Yield ranged from 4.9 to 6.7 t·ha-1, depending on the cultivar x water regime interaction (P<0.05). Under WW conditions, Algarrobo yielded 6.7 and AG-HB4.25 6.3 t·ha-1, whereas under WD conditions, Algarrobo yielded 4.9 and AG-HB4.25 5.9 t·ha-1. We can conclude that the expression of HaHB4 improved yield stability, because WD reduced grain yield by only 7% in the AG-HB4.25 cultivar whereas it caused a reduction of 26% in Algarrobo. Finally, a set of experiments were carried out under rain-fed conditions in different locations within the Argentine Pampas (from -32.6 to -38.4 latitude and from -58.2 to -64.3 longitude) for two years (n=12). The AG-HB4.25 cultivar yielded between 2% and 29% higher than Algarrobo, for a yield range from 3.2 to 7.7 t·ha-1. The response was associated with water deficit, estimated as the difference between rain and potential evapotranspiration during the reproductive stages of wheat (R2=50%, P=0.0078). The introduction of HaHB4 in the Algarrobo background increased yield at 0.225% per mm water deficit.