Dose reduction in pediatric nuclear medicine involves many aspects of nuclear imaging. The computed tomography (CT) parameters used during the new hybrid imaging procedures, positron emission tomography (PET)/CT and single photon emission computed tomography (SPECT)/CT, involve trade-offs between image quality and effective dose. In this setting, CT may be used for diagnostic quality imaging, localization of scintigraphic abnormalities or attenuation correction only, with markedly different radiation exposures for each technique. The nuclear physician must select administered activities for PET and single photon imaging that provide quality imaging results at the lowest possible radiopharmceutical dosage. These administered activities must be adjusted appropriately for patient mass or age. Physical differences between PET and single photon imaging may require different adjustments for patient size. Dynamic imaging protocols should be reviewed to assure that frame rates appropriately track physiologic events and facilitate low administered activities. Optimal dose reduction in pediatric nuclear imaging requires attention to CT exposure parameters, administered activity and imaging protocols.