Using saline water in agriculture to increase production areas requires knowledge of the effect of fertilizer supplements under saline water conditions. A trial was conducted under greenhouse conditions using pots of 4 kg with sand as a substrate. Three levels of water salinity were evaluated (1, 2.3, and 3.4 dS m-1) with three NP levels of fertilization (300-300, 150-150, and 0-0 mg kg-1) planting jalapeño pepper (Capsicum annuum L. ‘Everman’). A complete randomized block design was used in a factorial arrangement 3×3, with three replications. Biomass production (stem, leaves and fruits) production per pot was evaluated, and N, P, K, Cl, and Na tissue concentration was evaluated. The final ECe and pH of the substrate was determined. Foliage, stem, and root dry weight decreased as water salinity increased. Medium NP level of fertilization showed the best results. Poor results were observed when the lower level of NP fertilization and the highest water salinity was used, showing no fruit production. NPK extraction was higher when the high level of fertilization was used, but it decreased at the highest water salinity level. Cl and Na extraction increased as fertilization and water salinity levels increased. Final substrate ECe increased linearly as water salinity increased. Meanwhile, NP levels evaluated did not show a clear response. Final substrate pH decreased at the highest fertilization level, while no change was observed as a result of the water salinity. It can be concluded that a high-water salinity affects negatively jalapeño pepper production, that effect can be mitigated using an adequate fertilization level.