Objrctive: Efficacy and safety of fractional Co2 laser versus fractional Er:YAG in treatment of facial rhytides determination study .Design:randomized,double blined,parallel,phase1 clinical trial. Methodology: Target selection:Patients referring to Shohadaye Tajrish Educational Hospital a) Inclusion criteria:1)females between 35 and 75years of age 2)patients with mild to moderate facial rhytides at rest Exclusion criteria included: 1)males 2)females younger than 35 yerars old 3)pregnancy and lactatation 4)cosmetic procedures affecting the treatment area (e.g.,botulinum toxin, dermabrasion, chemical peeling, laser surgery, or face-lift) within the last 6months 5) oral isotretinoin within the last 6months 6) history of keloid formation 7)connective tissue disorders,8)major underlying disease,9)diabetes, 10)uncontrolled hypertension, 11)active infection in face area,13) personal history of skin cancer in face,14)unrealistic expectation,15)sensitivity to tetracaine or lidocaine Target sample size:35 b) Study interventions:Patients were randomly assigned to receive treatment on each side of face , one with a long pulsed Nd:YAG and one with a fractional Er:YAG laser. c)Time of the intervention:3 treatment sessions with 1 month interval for each patient d)Study outcome:The evaluation both before each treatment session and 3months after the last one will be done with reviscometer and digital photography as well as assessment of side effects (eg.,pain,stinging,pruritis,redness,bulla,bleeding,crust formation,hypopigmentation,hyperpigmentation,scar,atrophy)will be performed .