To compare the image quality and radiation dose between iterative reconstruction (IR) and standard filtered back projection (FBP) in CT of the chest and abdomen.Thoracic CT was performed in 50 patients (38 male, 12 female; mean age, 51±23yrs; range, 7–85yrs) and abdominal CT was performed in 50 patients (36 male, 14 female; mean age, 62±13yrs; range, 20–85yrs), using IR as well as FBP for image reconstruction. Image noise was quantitatively assessed measuring standard deviation of Hounsfield Units (HU) in defined regions of interest in subcutaneous tissue. Scan length and Computed Tomography Dose Index (CTDI) were documented. Scan length, image noise, and CTDI of both reconstruction techniques were compared by using paired tests according to the nature of variables (McNemar test or Student t test). Overall subjective image quality and subjective image noise were compared.There was no significant difference between the protocols in terms of mean scan length (p>0.05). Image noise was statistically significantly higher with IR, although the difference was clinically insignificant (13.3±3.0HU and 13.6±3.0HU for thoracic CT and 11.5±3.1HU and 11.7±3.0HU for abdominal CT, p<0.05). There was no significant difference in overall subjective image quality and subjective image noise. The radiation dose was significantly lower with IR. Volume-weighted CTDI decreased by 64% (6.2±2.5mGy versus 17.1±9.5mGy, p<0.001) for thoracic CT and by 58% (7.8±4.6mGy versus 18.5±8.6mGy, p<0.001) for abdominal CT.Our study shows that in thoracic and abdominal CT with IR, there is no clinically significant impact on image quality, yet a significant radiation dose reduction compared to FBP.