The aim of this study was to evaluate the radiopacity of a zinc oxide and eugenol-based (Endofill), a calcium hydroxide-based (Sealapex), two resin-based (Sealer 26 and AH Plus), and a silicone-based root canal sealer (Roeko Seal). Specimens, measuring 10mm in diameter and 1mm in thickness, were radiographed simultaneously with an aluminum step wedge using occlusal films, according to ISO 6876/2001 standards. Radiographs were digitized, and the radiopacity of sealers was compared to the different thicknesses of the aluminum step wedge, using the VIXWIN 2000 software. Results demonstrated that AH Plus was the most radiopaque sealer, while Sealapex was the least radiopaque (p<0.05). Roeko Seal, Endofill and Sealer 26 presented intermediate radiopacity values. Sealapex presented less radiopacity than the other types of root canal sealers.