Background: Molar incisor hypomineralization (MIH) describes the clinical picture of hypomineralization of systemic origin affecting one or more first permanent molar and incisors. Although the reported prevalence of MIH ranges from 2.4% to 40.2% worldwide, very little data is available from Nepal. Objective: To assess the prevalence of MIH in children aged 7-13 years of Biratnagar, Nepal. Study design: This cross-sectional descriptive study consisted of 567 children aged 7-13 years selected by cluster sampling method. Examinations were performed by one calibrated pediatric dentist. The European Academy of Pediatric Dentistry (EAPD) 2003 criteria was used for diagnosis. Results: The prevalence of MIH was 8.6% in the age group of 7 to 13 years. The prevalence of MIH was 8.33% in males and 9.01% in females. The prevalence and severity of MIH increased with increase in age. The prevalence of MIH was 10.54% in the age group of 10 to 13 years as compared to 5.95% in the age group of 7-9 years. Conclusion: The prevalence of MIH was 8.6% in the age group of 7 to 13 years. Developmental dental defects hold significance for scientists and practitioners from both medicine and dentistry. Dental interest has recently swung toward Molar Hypomineralisation. MIH imposes a significant burden on global health and has potential to become medically preventable, being linked to infantile illness.