INTRODUCTION: The personal frequency modulation system is an assisted technology resource used in the accessibility of individuals with hearing impairment, being very important in the school environment. Ordinance number 1274/2013 included this device into the Brazilian unified health system. OBJECTIVE: To analyze the distribution the personal frequency modulation system concession in the national territory by the Brazilian unified health system from 2013 to 2017. METHODS: This is an ecological study that uses the 27 federation units and the five geographic regions as analysis units. The population involved students in the age range of 5-17 years who reported severe hearing impairment. The data sources were the ambulatory information system/Brazilian unified health system, the Brazilian institute of geography and statistics and the report no. 58 of the national commission for the incorporation of technologies into Brazilian unified health system, national commission of technologies incorporation of the ministry of health. The spatial analysis was carried out through the percentage of coverage of the frequency modulation system concession per federation unit; the data were then unified in the five geographic regions and descriptive statistical analysis was performed. RESULTS: Between the first and second years, there was an increase of almost 50% in the quantity dispensed, however, there was a progressive decline in the following years. The average coverage of the frequency modulation system in Brazil was 33.4%. The spatial exploratory analysis showed there is a low and uneven distribution in the territory, as the South and Southeast regions had the highest coverage and the North and Northeast regions the lowest, except for the Rio Grande do Norte unit. CONCLUSION: The frequency modulation system concession was below that stipulated by the ministry of health and from 2014 to 2017, the dispensed quantity progressively decreased. There is an unequal distribution in the territory that can be explained by the geographic disposition of hearing health services.