The objective of the current study is to characterize dextran purified from Lactobacillus fermentum (Lb4) Isolates of Lactobacillus spp. were tested for dextran production using mucoidy, ethanol precipitation and spectrophotometric method. Results of the Spectrophotometric method showed that all isolates gave concentrations of dextran ranging from (0.1 to 0.2 mg/ml). Precipitation, purification and characterization of dextran from L. fermentum (Lb4) were done. Thin-layer chromatography (TLC), 1H Nuclear Magnetic Resonance (HNMR) Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FE-SEM), Gas Chromatography-mass spectrometry (GC-MS), Melting Point (MP), Water Solubility index (WSI), and Water Holding Capacity (WHC) had been used for dextran characterization. Characterization proved that pure dextran. Nanosphere structure with a nano-diameter range of about (56.00) nm with molecular weight (73) kDa. According to the melting point test, the purified dextran from L. fermentum had been completely melted at 228°C. The water solubility index (WSI) had been determined (93.35%) and the water holding capacity (WHC) (300%). Keywords: Lactobacillus spp. ; Dextran ; Lactobacillus fermentum