This in vitro study was carried out to assess the shear bond strengthof composite resin bonded to enamel and dentin pretreated with acidetchant and Er,Cr:Ysgg.Non-carious 66 sound human premolars were selected to prepare132 specimens for this study. Buccal surfaces were flattened and wereground under copious water coolant to obtain a flat enamel surface whilethe lingual surfaces were ground to obtain a uniform flat surface ofsuperficial dentin. Subsequently, the surfaces were polished with 240 grit,400 grit and 600 grit sandpaper disks to standardize the smear Layer.Prepared specimens were randomly divided into two main groups,66 specimens each, according to etching methods (A); group (A1) etchingby an Er, Cr: YSGG laser system (Waterlase MD, Biolase); and (A2)etching by phosphoric acid using Scotchbond Universal Etchant. Eachgroup was further divided into two subgroups 33 specimens eachaccording to tooth substrate tested (S); where (S1) was for enamel, while(S2) was for dentin. Each subgroup was divided into three classes 11specimens each according to storage time (T); stored for 1 day (T1),stored for 7 days (T2) and stored for 30 days(T3).The adhesive was applied on the substrate and cured then a plastictube (Tygon tube), 0.7 mm in diameter and 1mm in length was heldsecurely and immobilized using cotton pliers on the indicated substrate.Then resin composite (Z 350 XT) was packed into the tube and cured.Microshear bond strength test was conducted using universal testingmachine at crosshead speed of 0.5 mm/min till specimens fail, bondstrength was calculated in MPs.The results of the current study revealed that laser-etched enamelshowed the lowest significant microshear bond strength mean comparedto acid-etched enamel.