Objective: The aim of this study was to evaluate the effect of saliva contamination on the shear bond strength of the conventional adhesive and the self-etch primer/adhesive. Material and Methods: Eighty human maxillary premolars were used in this study. They were randomly divided into 2 equal groups. In group I (N=40), Monolok2 conventional adhesive was used to bond brackets to the enamel surface. In group II (N=40), Brajen Unibond self-etch primer/adhesive was used to bond brackets to the enamel surface without acid etching. Each group was further subdivided into 4 equal subgroups according to enamel surface condition. Premolar brackets were bonded to the teeth according to the manufacturer instructions. Each specimen was mounted in an Instron Universal Testing Machine and tested to failure in shear mode. Results: Results revealed highly significant differences between subgroups in group I and group II. Conclusion: Conventional bonding system is less reliable in different saliva contamination conditions. The behavior of the material was less predictable than the self-etch primer/adhesive system.