The purpose of this in vitro study was to compare the shear bond strength of different types of sealant to non-contaminated and saliva-contaminated enamel. The buccal surfaces of 60 sound permanent third molars were individually embedded in self-curing acrylic resin and wet ground with 1,000-grit silicone carbide paper to obtain a flat enamel surface. The specimens were randomly assigned to one of three groups: 1) non-fluoride-releasing resin sealant (Concise), 2) fluoride-releasing resin sealant (Clinpro), 3) glass-ionomer sealant (Fuji VII). Each group was divided into 2 subgroups (n = 10): non-contaminated and saliva contaminated with 0.02 ml of fresh human saliva for 20 seconds and then blowed dried prior to sealant placement. All samples were thermocycled 2,000 cycles. The specimens were tested using an Instron running at a crosshead speed of 0.05 mm/min. Stereomicroscope examinations were carried out to evaluate failure sites of the sealants. Data were analyzed with one-way ANOVA and the Turkey test at a siginificance level of p < 0.05. Comparison of the different types of sealant revealed the shear bond strength of the glass-ionomer sealant was the same for the non-contaminated and saliva-contaminated subgroups. The shear bond strength was lower in both the fluoride and non-fluoride releasing resin-based sealant groups contaminated with saliva than in the fluoride and non-fluoride releasing resin-based sealant groups not contaminated with saliva. Comparison of the different types of sealant also revealed the shear bond strength of the glass-ionomer sealant had a significantly lower shear bond strength than the fluoride and non-fluoride releasing resin-based sealant groups for both the non-contaminated and saliva-contaminated subgroups. The fluoride and non-fluoride releasing resin-based sealant groups were not significantly different from each other. The modes of failure were mostly mixed with the glass-ionomer sealant in both the non-contaminated and saliva-contaminated subgroups of this sealant. The resin-based sealant groups (both fluoride and non-fluoride releasing) had cohesive/mixed failure in the non-contaminated and adhesive/mixed failure in the saliva-contaminated subgroups. In conclusion, saliva-contamiantion did not affect the shear bond strength of glass-ionomer sealant but the glass-ionomer sealant had the lowest shear bond strength.