Introduction <p>Since the introduction of computed tomography (CT), there has been a progressive concern about its associated radiation risk. This study aims to compare the radiation effective dose (ED) of abdominal CT examination calculated by two different methods.</p> Material and methods <p>Dosimetric data of abdominal CT examination were used to calculate ED for 73 adult patients: 41 males and 32 females. For each participant, the ED was calculated three times. The first and second times were by the use of DLP-to-ED conversion factors (<i>k</i>-coefficients), which were published by the European Commission (EC) and specifically published for SOMATOM Definition SA / Siemens CT machine. The other method included the calculation of ED based on organ dose, which were obtained by CTDI_vol to organ dose conversion factors.</p> Results <p>The ED calculated by both machine-specific DLP-to-ED conversion factor and organ dose method tends to be comparable 7.96 and 8.05&#xa0;mSv, respectively. A smaller ED was obtained by the use of EC’s DLP-to-ED conversion factor, 7.42&#xa0;mSv. However, these variations are statistically non-significant. For all calculation methods, ED was higher for female patients than for male patients.</p> Conclusion <p>The abdominal CT ED estimated in this study was within the internationally recommended levels. However, sex-specific ED calculation may be recommended.</p>