Aim: to evaluate and compare the effect of moisture on the apical seal of five different types of sealers (epoxy resin-, methacrylate resin-, silicone-, calcium hydroxide- and zinc oxide and eugenol based root canal sealers). Methodology: One hundred and twenty (120), single canaled, human, permanent teeth were collected for this study. 20 specimens were equally divided into negative (N) and positive (Po) control groups. 100 specimens were divided into two equal experimental groups, 50 specimens each, according to the presence or absence of moisture in the canal before obturation. Each group was subgrouped into two equal subgroups Active (A) and Passive (P) according to the method of immersion in mythelene blue. Each subgroup was further divided into five divisions, 5 teeth each, according to the type of sealer used. Results: Results showed that there was a statistically significant difference between each of AH Plus, RealSeal SE and Roekoseal on one hand and Endofill and CRCS on the other hand, a statistically significant difference was found between Endofill and CRCS. Conclusions: It was concluded that controlled moisture contamination did not affect the sealing ability of epoxy resin- and silicone-based root canal sealers and even improve the sealing ability of methacryalte resin-based root canal sealer while it adversely affects the sealing ability of calcium hydroxide- and zinc oxide and eugenol-based root canal sealer