OBJECTIVE To evaluate in vitro the microleakage of various dentin bond/resin liner systems when used with both a spherical and an admixture alloy. METHODS Class V cavity preparations were prepared on 60 noncarious extracted human molar teeth with one margin in enamel and another in dentin and restored with either Dispersalloy or Tytin alloy. Treatment groups utilizing either no liner, Copalite varnish, Amalgambond Plus/HPA, Tenure with Panavia EX Dental Adhesive, Syntac with Dual Cem, and All-Bond 2 with Liner F were tested. Samples were thermocycled, stained, and sectioned to evaluate microleakage. RESULTS A significant reduction in microleakage at the enamel and dentin margins was found in all dentin bond system/resin liner groups when compared to unlined and Copalite-lined alloys. There were no significant differences in total microleakage scores between the alloy types. Statistically significant differences in microleakage were detected between some systems. The Tenure with Panavia EX treatment group exhibited a significantly lower total microleakage when used with Tytin. The Syntac/Dual Cem treatment groups exhibited a significantly higher total microleakage when used with Dispersalloy.