Abstract: The effect of salinity stress alone and with foliar application with 100 ppm riboflavin (vit. B2) on seedling growth, organic solutes accumulation, ion uptake and the activity of antioxidant enzymes in Hibiscus sabdariffa L. was investigated. Analysis of data (ANOVA) revealed that, growth of Hibiscus sabdariffa L. seedlings was reduced with increasing NaCl concentration, while water content and dry matter were not changed significantly at the low levels of salinity. Soluble carbohydrate, protein and proline were found to be increased significantly. The content of Na+ was significantly increased, while K+ as well as K+/Na+ and Ca++/Na+ ratios were decreased as salinity levels increased. Calcium and total cations were slightly affected. Foliar application with vit. B2 induced stimulatory effects on almost measured parameters. On the other hand, Na+ content decreased significantly. Further, salinity induced marked increases in lipid peroxidation and the activity of antioxidant enzymes (CAT, POD, APX and GR), while membrane stability index was significantly decreased. Spraying of salinized seedlings with vit. B2 induced a marked increase in MSI and antioxidant enzymes, whereas the content of lipid peroxidation was decreased in comparing with salinized seedlings. Results suggest that, vit. B2 may have a potential role as an effective antioxidant by regulating osmotic and ionic balance and enhancing the resistance of H. sabdariffa L. seedlings to salinity stress.