Soil salinity is a worldwide problem. The aim of this study was to evalu ate biomass production and partition in the organs of sunflower under a gradi ent of salinity in the soil. The Victoria sunflower was sown on 15 June 2007 at a density of 100,000 plants ha-1 in Montecillo Mex. (19° N, 48° W and 2,400 m). The area has an arid climate (less dry), an annual rainfall of 558.5 mm, and an average temperature of 14.6°C. Based on soil analysis, three areas were used as the treatments, each having 4 replicates. These were: high salinity (EC 11 dS m-1, HS), medium salinity (EC 7 dS m-1, MS), and low salinity (EC 5 dS m-1, HS). Crop emergence occurred eight days after sowing (DAS), anthesis (R5) 80 DAS, and physiological maturity (R9) 130 DAS. Dry matter accumula tion (%) in plant organs, total biomass, yield and survival all decreased with increasing salinity, whereas DM distribution did not. The highest biomass, yield and survival were found in the LS treatment (1055, 102 g m-2, and 100%), while the lowest values of these parameters were recorded in the area with HS (312, 29 g m-2, and 60%), respectively. The greatest dry matter accu mulation was observed in the stem, followed by the receptacle, seeds and leaves. The harvest index and the filled capitulum index were not affected by salinity. In conclusion, biomass accumulation, yield and survival of sunflower decreased with increasing soil salinity. The phenology and biomass distribu tion in the plant organs were not affected by salinity.