Insufficient intake of iodine or consumption of foods containing goitrogens can decrease thyroid function leading to multiple physical and mental disorders known collectively as iodine deficiency disorders. Successful implementation of the universal salt iodization strategy, which is the main intervention strategy for the control and elimination of iodine deficiency, requires constant monitoring. Urinary iodine concentration is the recommended biochemical indicator for assessing the iodine status of a population. The present studies were prompted by the apparent lack of published data on the status of iodine nutrition among school-age children in Morobe and Eastern Highlands provinces in Papua New Guinea (PNG). The aims of these studies were to determine the urinary iodine concentration in school-age children (6 – 12 years) as a way of assessing the impact of the salt iodization programs in Morobe and Eastern Highlands Provinces in PNG. These prospective school based cross-sectional studies were carried out in Aseki-Menyamya district Morobe province and Gouno, Mt. Michael Local-Level Government area in Lufa district Eastern Highlands province, PNG. Simple random sampling was used to select primary schools in each district. The iodine content in salt samples was measured using the single wavelength semi-automated WYD Iodine Checker Photometer. Urinary iodine concentration (UIC) was estimated using the Sandell-Kolthoff reaction. In Lufa district, the mean per capita discretionary consumption of salt was 4.7 ± 2.1g per day with a range of 2.1 – 9.6g; the mean iodine content in salt samples from the households was 17.8 ± 4.5ppm; the iodine content was below 15ppm in 23.8% of all the salt samples. For the children in Aseki-Menyamya district, the median UIC was 149.5μg/L, Interquartile Range (IQR) was 70.0 – 300μg/L; the UIC was below 100.0μg/L in 32.9% of the children and 17.9% had UIC below 50μg/L. For children in Gouno Lufa district, the median UIC was 50.0μg/L, IQR was 23.9 – 76.0μg/L, 87.9% had UIC below 100.0μg/L, and 49.2% had UIC below 50.0μg/L. The results indicate that iodine deficiency should be considered a significant public health problem among the school-age children in Gouno Lufa district. Our findings indicate the urgent need for efficient, sustainable, systematic and functional monitoring system to strengthen and improve on the implementation of the USI strategy in both districts.