Background: Developmental defects of enamel especially enamel hypomineralization are prevalent among children. Hypomineralized second primary molars (HSPM) present a serious clinical dilemma for the current practitioners. It represents as a potential predictive factor for molar incisal hypomineralization (MIH). The reported prevalence of HSPMs in India however still remains uncertain. Methodology: A total of 649 children aged 6–10 years were randomly selected from various schools in Delhi NCR. The teeth were indexed for developmental defects of enamel using modified European Academy of Paediatric Dentistry judgment criteria given by Ghanim et al. Results: A total of 83 HSPMs were observed in 33 of the 649 subjects examined, with a prevalence of 5%. Molars affected had prevalence of 62.88%, with two deciduous molars being most commonly affected. Of the defects present, creamy white opacities were most common followed by yellowish brown opacities. Posteruptive breakdowns (PEB) were more commonly associated with yellowish brown opacities. Conclusion: The prevalence of HSPMs in Delhi, NCR was 5%. Creamy white opacities were the most common lesion present.