This study was performed to evaluate the micro shear bond strength of resin composite bonded to enamel and dentin pretreated with acid etchant or Er,Cr:Ysgg. M & M: 66 premolars were selected.Buccal and lingual surfaces were flattened.Teeth were randomly divided into two main groups according to etching methods (A); group (A1) etching by an Er, Cr: YSGG laser and (A2) etching by phosphoric acid. then each group was subdivided into two subgroups according to tooth substrate tested (S1) was for enamel, while (S2) was for dentin. Each subgroup was divided into three classes 11 specimens each according to storage time (T); stored for 1 day (T1), stored for 7 days (T2) and stored for 30 days (T3). Teeth were restored for microshear bond strength testing using universal testing machine; load was applied till specimen's fail. Results: both laser-etched enamel and dentin showed lowest microshear bond strength mean compared to acid-etched one. Conclusion: Etching with Er,Cr: YSGG laser impair the micro shear bond strength of resin com­posite to enamel and dentin and does not constitute an alternative to its acid etching.