Abstract Plant responses to salinity and herbivory have been primarily studied separately. However, in natural settings, plants are affected simultaneously by several factors. Because of an overlap in signaling pathways between plant responses to salinity and to herbivory, responses to one factor could be enhanced or lessened by exposure to the other. To investigate the interaction of the responses to these two stress factors, four cultivars of hybrid poplars (Populus) were used to determine if salt tolerance affects resistance to insect herbivory by Orgyia leucostigma. Hybrid poplar seedlings in hydroponics were exposed to 0, 50, and 100 mM NaCl for either two- or three-week treatment periods. Salt exposure resulted in decreased leaf photosynthesis, transpiration, and stomatal conductance, while chlorophyll fluorescence, chlorophyll a, lignin, phenolic compounds, proline, and glycine betaine content of leaves were not affected by salinity. Jasmonic acid (Ile) was found to increase in Walker cultivar at the lowest salt concentration but was not affected at the highest salt concentration. Elemental composition varied between the four cultivars, as noted between leaves that expanded either prior to or during salt exposure at the highest concentration. This included increased nitrogen (Only in Can Am and Okanese pre-salt treatment leaves) and phosphorus (Only in Assiniboine and Walker post-salt treatment leaves), while calcium contents decreased regardless of leaf age/position on the plant. Sodium content increased regardless of leaf age/position on the plant of all cultivars at 50 mM NaCl except for Okanese plants. Constitutive and induced resistance to herbivores, estimated from leaf disc feeding assays were not significantly affected by salinity despite changes in the nutritional value of salt-exposed leaves (cultivar dependent: increase or decrease in total soluble carbohydrates, decrease in proteins, and increase in Na/K ratio). These results suggest that feeding preference of O. leucostigma (2nd instar larvae) was not altered by hybrid poplar response to salinity.