Guava is a fruit crop widely exploited in the Northeast region of Brazil. However, its exploitation is limited by water scarcity and, in many cases, producers are forced to use water with high levels of salts in irrigation. Thus, it is necessary to develop techniques to induce plant tolerance to salt stress, and the foliar application of a non-enzymatic compound such as ascorbic acid is a promising alternative to mitigate the deleterious effects on plants. The objective was to evaluate the effects of foliar application of ascorbic acid on guava plants, irrigated with saline waters in the seedling formation phase in a semi-arid region. The experiment was carried out in a greenhouse adopting a randomized block design, in a 5 × 4 factorial scheme, with five levels of electrical conductivity of water - ECw (0.3, 1.3, 2.3, 3.3 and 4.3 dS m