Background: Grades of malnutrition can be classified and diagnosed by various available methods like IAP, WHO-Z score, Waterlow, Gomez and various parameters like anthropometric measurements. All these methods are also used to compare incidence and prevalence of malnutrition between different age groups. This study was done to compare the IAP vs WHO-Z score classification in precisely assessing the malnutrition status of children aged 0 to 5 years. Methods: This multicentric prospective comparative study was conducted at twenty-five ICDS centers in Karaikal, Puducherry between 2017-2019. Eligible study population included 0-5 years old children whose parents were willing to give consent at the time of enrollment. A thorough clinical examination was done to diagnose various nutritional deficiencies. Comparison was done between IAP and WHO classification of degrees of malnutrition. The comparison groups were analyzed using chi-square test. Results: A total of seven-hundred children were assessed for malnutrition, classified into various grades using IAP and WHO-Z score. Comparative analysis was done between two groups from each grade of malnutrition and it was observed that WHO-Z score classification and IAP classification didn’t have significant difference in identifying moderate malnutrition but WHO-Z score was significantly better (P=0.0001) in precisely identifying severe malnutrition. Conclusion: This study indicates that severe malnutrition which is still prevalent as assessed by IAP and WHO-Z score can be more precisely diagnosed using WHO-Z score [WAZ-7.8%, WHZ-3.8%, Grade III & IV-3.5%]. IAP grading is a time-tested method, which is easy to use and all categories of health workers were already accustomed to use it. A new tool incorporating WHO-Z scores in the existing IAP grading can be evolved for an accurate assessment of severe malnutrition