Abstract : This work aims to assess the influence of pre-treatment with chlorhexidine and fluoride solutions on shear bond strength "SBS" of sapphire brackets bonded using two types of orthodontic adhesive systems. Forty recently extracted premolars were allocated to 4 equal experimental groups, 1st and 2nd were treated with 0.20 % chlorhexidine gel, while 3rd and 4th were treated with Fluoride Varnish. Following surface treatment, sapphire brackets were bonded with Transbond XT plus (SEP) and Transbond XT adhesive group 2 and 4; and Heliost composite were performed for group 1 and 3 following the manufacturer’s specifications. The SBS was measured by a universal testing machine, while the failure sites were analyzed using the adhesive remnant index (ARI). The SBS for group 1 and 2 were less than those for group 3 and 4 without a statistically significant difference (P> 0.05); however, significantly greater bond strength (P< 0.05) was found between groups 1 (treated with chlorhexidine gel) and group 3 (treated with fluoride varnish). No significant difference in SBS was observed between HELOISIT and XT TRANSBOND PLUS primer and adhesive. ARI scores showed that failures mostly occurred at the interface of enamel and resin. The application of chlorhexidine gel before bonding had insignificant impact on the SBS; however, fluoride varnish significantly increased SBS for Heliosit adhesive