Introduction: Iodine deficiency disorders are common endocrinopathies in Nepal. Children are at risk for iodine deficiency disorders. Irreversible mental retardation and brain damage in children are the devastating disorders lead by iodine deficiency. Therefore, the main objective of the study was to find out the prevalence of insufficient iodine level among the children of a secondary school. Methods: This descriptive cross-sectional study was conducted in urine from April 2019 to July 2019 after obtaining ethical approval from Nepal Health Research Council (Registration number: 802/2018). Forty-six urine samples were collected from school children for iodine estimation. Convenience sampling was done. Data were entered into Statistical Package for the Social Science version 21 and descriptive analyses were done. Point estimate at 95% confidence interval was calculated along with frequency and proportion for binary data. Results: Among the 46 students, majority 36 (78.30%) (95% Confidence Interval= 66.30-90.21) of the school children had insufficient urine iodine level. Among 36 salt samples collected from school children with low urine iodine level, 8 (22.2%) salt samples had iodine less than 15ppm. Conclusions: Iodine estimation revealed a very high percentage of urine samples containing insufficient levels of iodine is similar as compared to studies done in similar settings. Hence, the school children were at risk of iodine deficiency disorders. Iodine deficiency disorders prevention programs should be priority intervention based on available evidence.