The aim of this study was to compare coronal microleakage in two conditions. Twenty-eight extracted upper molars were endodontically treated and divided into two groups and controls: group A: prefabricated post and core permanently cemented; and group B: prepared for a post and restored with a temporary post crown cemented with a temporary cement. The teeth were thermocycled, immersed in black India ink for 1 week, and made transparent. Results indicated that the permanently cemented, prefabricated post and core produced the best seal (p < 0.01); leakage was significantly greater with the temporary post crown and was similar to that of a positive control group.