Abstract: A greenhouse study was conducted on tomato plants (Lycopersicon esculentum Mill var. Roma) to monitor the effects of salt (NaCl) stress on dry matter yield and nitrogen (total and 15N) uptake. The significant difference in the dry matter production, total-N, and 15N content of plants, was first noted on day 15 of the 15N treatment, and this difference continued to the end of the study period. Moreover, differences in both the parameters i.e., dry matter production and 15N uptake, also appeared in the last (30 days) harvest between the two saline treatments.