Regarded to be a messenger molecule in recent years, effects of nitric oxide (NO) have been revealed under biotic and abiotic stress conditions. This study explores a possible relationship between salt stress and NO in Glycine max L. (soybean). The 6-days-old G. max seedlings were pre-treated with sodium nitroprusside (SNP), used as NO donor at different concentrations, and carboxy-2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide (c- PTIO), a synthesized NO scavenger, for 2 days. Afterwards, the seedlings were taken into hydroponic culture containing 100 mM NaCl prepared in 1/2 Hoagland solution. At the end of the experiment, relative water content (RWC), chlorophyll and carotenoid amounts, peroxidase (POD) activity and proline accumulation were determined on different parts (cotyledone and leaves) of the 19-days-old seedlings. Recovered RWC, chlorophyll and carotenoid destruction, reduced POD activity and increased proline accumulation were observed in the seedlings pre-treated with NO and exposed to salt. One can put forward as a result that certain negative effects were partly avoided by the exogenous application of SNP, and that c-PTIO abated the effects of NO. In addition, NO may play a role in the salt tolerance of G. max seedlings, with the concentration of SNP being quite important.