Amorphous Calcium Phosphate (ACP) has a lot of appeal due to its ability to arrest demineralization and/or remineralize defective enamel structures through the release of calcium and phosphate ions. ACP has been incorporated in recent years in a variety of dental materials from mouth washes to composite resins, as well as the focus of our study, prophylaxis pastes. Objective . The aim of this study is to investigate the bond strength of orthodontic brackets after bonding to an enamel surface which has been prepared using prophylactic paste containing ACP as well prophylactic pastes containing fluoride. Materials and methods. 80 human molars were sectioned into 160 buccal and lingual halves which were mounted in acrylic blocks exposing the enamel surface. The blocks were then randomly distributed according to the type of prophylactic paste used to clean the enamel surface into four groups: 1- Control, using a paste which does not contain an active ingredient (Glitter, Premier). 2- Paste which contains fluoride (Glitter, Premier). 3- Paste which contains Amorphous Calcium Phosphate (Enamel Pro, Premier). And 4- Paste which contains Amorphous Calcium Phosphate and Fluoride (Enamel Pro, Premier). Each group is further subdivided according to bonding technique into: A- 2 step bonding system (Ortho Solo,Ormco). B- 1 step bonding system (Clearfil S3 Bond, Kurary) to bond the molar brackets onto the prepared enamel specimens. Tensile bond strength is recorded. Results. A one way Anova and a two way Anova were used to compare the results. Statistically significant lower bond strength in enamel specimens which are prepared with pastes containing active ingredients (Groups 2, 3, 4) compared to the control group (Group 1) was found when using the 2 step bonding system. The bond strength was not different among the groups when using the 1 step bonding system. Statistically significant lower bond strength was observed when using the 1 step bond system as compared to the 2 step bonding system.