Germination of seeds is a crucial stage in plant life cycle. It is known that NO also plays an important role in seed dormancy and germination. Lentil is one of the most important crops in Turkey. Hence we chose this plant as an experimental material. The aim of the study is to examine effects of four different concentrations of SNP (0,01 μM, 100 μM, 600 μM and 700 μM), a NO donor, on lentil seeds. We established germination rate, primary root length, protein amount, activities of enzymes such as amylase, acid phosphatase, protease as well as mitotic index at 0, 24, 48 and 72 hours. We found that 100 μM SNP induces germination of lentil seeds, whereas 700 μM SNP clearly inhibits it. It was also established that 100 μM SNP was highly effective in primary root length and acid protease activity. Total soluble protein amounts were found to be higher than the control group in all SNP applications depending on the concentrations, and the most obvious increase was seen in the application of 700 μM SNP which also enhanced amylase activity. All SNP applications had the same effect on acid phosphatase activity, whereas acid and neutral protease activities changed depending on time and concentration. In addition, it was established that 700 μM SNP caused a reduction in mitotic activity. In the light of the fi ndings obtained in this study, it can be claimed that depending on the concentration, As a result, NO has a noteworthy effect as a plant growth regulator on the germination of lentil seeds