Abstract This study analyses the ambient dose equivalent around transmission full-body scanners used in Brazilian prisons and airports. In order to achieve this goal, three transmission full-body scanners of the same model assembled by a Brazilian manufacturer were evaluated. Ambient dose equivalent rates were measured at several positions around these screening devices with the help of an ionisation chamber made by Ludlum, model 9DP. These systems consist of an X-ray generator with three distinct modes of operation, each with a unique value for maximum energy (100, 150 and 160 keV) and current (0.4, 0.5 and 0.9 mA). Results show the integrated dose per scan at each of the measurement positions considered, presenting values for ambient dose equivalent with and without an individual being scanned, in order to take into account the scattering due to the presence of a human body.