The purpose of this study was to investigate in vitro the effect of using hot endodonic pluggers for immediate dowel space preparation on the apical seal of endodontically treated teeth filled by a chloropercha technique. The results demonstrated that, when the coronal half of the root canal filling material was removed immediately after placement with pluggers, there was a loss of the apical seal and leakage in thirteen of twenty teeth. There was also leakage in thirteen of twenty teeth in which dowel spaces were not prepared. This study did not demonstrate a significant difference statistically in loss of apical seal and leakage between teeth prepared with and those without immediate dowel space preparations with pluggers using a chloropercha filling technique. Immediate preparation of the dowel spaces had no effect on the apical seal. The chloropercha technique by itself showed evidence of very high leakage when used to fill the root canal.