Objective To compare the apical microleakage of Vitapex（calcium hydroxide based paste） with that of AH- plus and zinc oxide eugenol sealer when used with laterally condensed gutta percha obturation technique. Methods One hundred single rooted human anterior teeth were instrumented and randomly divided into three experimental groups（A, B, C） of 30 teeth each and two control groups（D, E） of 5 teeth each. Group A was filled with laterally condensed gutta- percha using Vitapex as sealer. Group B was filled with laterally condensed gutta - percha using AH- plus as sealer. Group C was filled with laterally condensed gutta- percha using zinc oxide eugenol as sealer. Group D was the positive control. Group E was the negative control, which were coated with nail polish to entire root surface. Teeth were then suspended in 2% methylene blue. After this, teeth were demineralized dehydrated and cleared. Linear dye penetration was determined under stereomicroscope with calibrated eye piece. Results The mean dye penetration for group A, B, C were respectively（0.57±0.56）mm, （0.79 ±0.96）mm and（1.07 ±1.12）mm. Group D demonstrated maximum dye penetration. Group E showed no dye penetration. There was no statistically significant difference between group B and group C（P>0.05）. However, there was statistically significant difference between group A and group B, C（P
