This study evaluated the marginal sealing ability of direct and indirect (inlay) resin composite restorations with three dentin bonding systems. Forty-eight freshly extracted bovine incisor teeth were randomly assigned to four groups for bonding with Syntac Single-Component, Excite (Vivadent, Liechtenstein), ScotchBond Multi-Purpose Plus (3M Dental Products, St Paul, MN 55144, USA) and a control with no bonding agents. Class V cavities were cut in both buccal and lingual surfaces. The coronal half of each preparation was in enamel and the gingival half was in cementum or dentin. Half of the specimens in each group were restored with direct and the remainder with indirect technique. The teeth were stored in 37 degrees C water for 30 days, then thermocycled. After immersion in 0.5% basic fuchsin, the teeth were cut faciolingually and evaluated for dye penetration using a binocular stereomicroscope. There was no significant difference among the bonding systems for either the direct or indirect technique or between the two techniques used for each system, however, the indirect technique showed significantly (p = 0.001) less microleakage than the direct technique in control groups. All groups showed more leakage at the cementum margins except Excite with direct technique, where microleakage at the incisal and gingival margins was almost equal.