The value of the use, by the health agents in Rondônia, Brazil, of the nutritional classification proposed by the Multidisciplinary Research Center for Rural Development (CIMDER), Colombia, known as the three color CIMDER band, is analyzed. The band, used to measure arm circumference, would be used as an instrument for the detection of nutritional risk in children under five years of age and for refering them to larger, more complex, health units. For this purpose, a sample of 1,268 children were studied. The results of the nutritional classification obtained by the band and the results of Gomez classification were compared. The application of the validations tests resulted in the following values: sensibility = 77.1%; specificity = 68.8%; positive predictive value = 59.0%; negative predictive value = 83.7%; rate of false positives = 31.2% and rate of false negatives = 22.9%. Except for the rate of false positives, the rest of the results were considered to be satisfactory, sufficiently so to recommend the use of the CIMDER band as an instrument of selection by the health agents in Rondônia. More specific indicators should be adopted at the larger, more complex health units, with a view to reducing the number of false positives in the programs for attendance to the undernourished.