The current study was designed to investigate the utilisation of three form of chitosan in manufacture of yoghurt during storage at 4-6°C up to 21 days. The first treatment was adding the particles in its commercial form, the second in the form of nano particles with the same concentration as the commercial form, while the third was added nano particles at half of the concentration in the commercial form. Treatments were coded CHC, CHNPs(5mg) and CHNPs(2.5mg) respectively. All treatments subjected to physiochemical, microbiological,DPPH and organoleptic assessment. Results indicated that the pH values increased in all fortified yoghurts especilly CHNPs(5mg) (4.50) compared with control. No clear differences in protein and fat % of fortified yoghurt with commercial and nano sized Chitosan. Syneresis was reduced in CHNPs treatments as compared to control samples. According to data, the control group's DPPH radical scavenging activity was shown to be lower. Data were reported that DPPH radical scavenging activity was found to be lower in the control. Data were reported that DPPH radical scavenging activity was found to be lower in the control. However, adding CHC and CHNPs increased the DPPH radical scavenging activity more than control. LAB in yoghurt were significantly decreased with increasing the concentrations of nano particales CHNPs(5mg), However, coliform bacteria were not found in any treatments while they were being stored in the cold. The information gathered indicated that the inclusion of CHNPs (2.5 mg) could be necessary during production of yoghurt without having a negative impact on its organoleptic qualities.