The present study was conducted to determine the influence of 2 intracanal medicaments (calcium hydroxide, chlorhexidine gel 2%) when used either alone or combined on the short- and long-term sealing ability of permanent root canal fillings. Ninety human upper central incisors were divided into 4 experimental groups (n=20). All root canals were instrumented in a step-back motion and then treated as follows: group I, root canal dressing with calcium hydroxide for 2 weeks and then obturation with laterally compacted gutta-percha and AH26 sealer; group II, chlorhexidine gel 2% for 2 weeks and obturation as in group I; group III, dressing with a new paste made by mixing calcium hydroxide plus chlorhexidine gel 2% for 2 weeks and obturation as described previously; group IV, immediately obturated with laterally compacted gutta-percha and AH26 sealer. Leakage along root canal fillings was measured using the transport fluid model. Short term measurements were carried out for 3 hours after 24 hours equilibrium establishment. Leakage was measured again at 6 months after the initial measurement. At 3 hours, no significant differences were found among the 4 experimental groups. Long-term measurements showed that also at 6 months no significant differences were observed between the group IV and the other 3 experimental groups. Under the conditions of the present study, it could be supported that none of the medications used seemed to affect negatively neither the short- nor the long-term sealing ability of the tested obturation technique. On the basis of these results and because of its increased antimicrobial action as it is supported in the literature, the new paste made of calcium hydroxide plus chlorhexidine gel 2% can be proposed for use in clinical practice without affecting the sealing ability of root canal obturation.