BACKGROUND: Iodine deficiency is a major public health problem all over the world, particularly among preschool children and pregnant women in low-income countries like Ethiopia and it is known to be the most common cause of preventable brain damage. OBJECTIVES: To determine urinary iodine concentration and to assess the level of iodine deficiency disorders. METHODS: A cross-sectional study was conducted in 380 randomly selected primary school children to determine urinary iodine concentrations as to assess level of iodine deficiency and associated factors in Bahir Dar town. Questionnaire: Include questions about sex, Age, Educational status, religion, Income, Occupation, Family size, Use cover for their salt container, Place of salt storage, Exposure to sun light, Duration of salt storage at house hold level, Place of salt purchasing, Time of adding salt to the prepared food. Laboratory investigations: Sandell- kolthoff reaction was done to determine the urinary iodine excretion. Initially the urine is digested in strong acid at high temperature; thereafter the color change of ammonium sulfate with another substance (arsenic acid) is accelerated by iodine as catalyzing agent. The speed of the change in color depends on the iodine concentration. Comparing to standard solution with known iodine content was performed with colorimeter. This reaction, which is called the Sandell-Kolthoff reaction (WHO, 2001) .The ceric ion, has a yellow color, while the Cerous is colorless. Colorimeter was used for estimation the urinary iodine concentration. RESULTS: The median U-I concentration was 241 µg/l (ranging from 5 to 850 μg/L) with Std. Deviation (137.2) the large standard deviation indicates the large difference in values of urinary iodine excretion in studied schoolchildren. The study revealed that the majority of highest levels (above500µg/l) of urinary iodine excretion were observed to be in government schools, 19 cases are (above500µg/l) And 13 of them are from government schools. 9.1% of school children has UIC >100 µg/l. CONCLUSIONS: This study showed that high urinary iodine level is present in the studied population and it has public health implication. Despite remarkable progress in the control of the iodine deficiency disorders (IDD), it remains a significant global public health problem.