The two traditional methods for the assessment of iodine deficiency in a given area are the estimation of urinary excretion of iodine, and the prevalence of goiter. In field studies, the estimation of urinary iodine excretion (UIE) in random urine specimens provides an adequate assessment of a population's iodine nutrition. The recommended method is the classic one, based on Sandell-Kolthoff reaction (Method A). Recently, a new semi-quantitative method has been introduced (rapid urinary iodide test [RUIT]). We performed a field study in a developing country (Azerbaijan) in order to compare the classic Method A to RUIT. The study included 942 schoolchildren, to whom UIE was estimated by RUIT. Comparing the two methods, (n = 260), the sensitivity of RUIT using as gold standard Method A, was 96% and the specificity was 61%. The correlation between median values UIE estimated by RUIT and by Method A was excellent (r = 0.98, p < 0.001). An agreement in iodine deficiency classification according to the World Health Organization-United Nations Children's Fund-International Council for the Control of Iodine-Deficiency Disorders (WHO-UNICEF-ICCIDD) between the two methods was observed in eight of nine areas. In conclusion, RUIT is a suitable method for UIE estimation in field studies of suspected iodine deficiency. The test is relatively inexpensive, easy to perform, and does not require sophisticated instruments.