Iodine is the micronutrient needed for synthesis of thyroid hormones. Excess or lack of iodine will cause disruption of thyroid function. The results of previous studies indicate that there is an increased prevalence of excess iodine in school-age children. The purpose of this study was to determine the determinants of excess iodine in school-age children aged 6 to 12 years in Demak, Grobogan, and Dharmasraya Regencies. The number of sample of school-age children was 750 in three district, with the inclusion criteria for length of stay in the study area was >6 months, and the exclusion criteria was they did not have severe illness. The status of iodine was measured through iodine content in urine using spectrophotometric methods. To determine iodine intake, iodine levels were measured in salt and in water, and the interview used food frequency questionaire (FFQ). The results showed that the iodine status of respondents in Dharmasraya Regency was at the optimal category (EIU: 225 µg / l, whereas in Demak and Grobogan districts the iodine were at excess category (EIU: 446 /l and 453µg / l) with the intake source came from drinking water and noodles (more than 10 ppb). It can be concluded that the determinants of excess iodine in three locations were iodine levels in drinking water, and noodles with consumption >3 times per week. It is recommended that the iodized salt program in the three research locations needs to be reconsidered. Keywords: Determinant, iodine, excess ABSTRAK Iodium adalah mikronutrien yang diperlukan untuk sintesa hormon tiroid. Kelebihan maupun kekurangan iodium akan menyebabkan gangguan fungsi tiroid. Hasil penelitian sebelumnya menunjukkan bahwa terdapat peningkatan prevalensi ekses iodium pada anak sekolah. Tujuan penelitian ini adalah untuk mengetahui determinan ekses iodium pada anak usia sekolah 6 sampai dengan 12 tahun di Kabupaten Demak, Grobogan dan Dharmasraya. Jumlah sampel anak sekolah sebanyak 750 anak usia sekolah di tiga kabupaten tersebut, dengan kriteria inklusi lama tinggal di wilayah penelitian lebih atau sama dengan 6 bulan, dan kriteria ekslusi tidak memiliki sakit berat. Status iodium diukur melalui kadar iodium dalam urin menggunakan metode spektrofotometri. Untuk mengetahui intake iodium, dilakukan pengukuran kadar iodium dalam garam dan dalam air dan wawancara menggunakann food frequency questionaire (FFQ). Hasil menunjukkan bahwa status iodium responden di Kabupaten Dharmasraya dalam kategori optimal (EIU: 225 µg/l, sedangkan di Kabupaten Demak dan Grobogan dalam kategori ekses iodium (EIU: 446 µg/l dan 453 µg/l) dengan sumber intake berasal dari air minum dan mie (lebih dari 10 ppb). Dapat disimpulkan bahwa determinan ekses iodium di tiga lokasi adalah kadar iodium dalam air minum dan mie dengan konsumsi lebih dari 3 kali per minggu. Disarankan pemberian garam beriodium di keitga lokasi penelitian perlu dipertimbangkan kembali. Kata kunci: Determinan, ekses, iodium