1) objectives: A comparison between corticosteroid injection versus loanaesthetic in treatment of lateral epicondylitis. 2) Design: Randomizedcal clinical trial. 3) Setting and conduct: Group A will receive Corticosteroid injection (Methyl-prednisolon acetate 1 ml) single dose into the painfull zone, Group B will receive a local anesthesia (procaine 2% 1 ml). VAS and Quick DASH questionnaires will completed at the baseline, and then 3, 6, 12 weeks after treatment. Also, each patient will fill demographic questionnaire including age, gender, first refer time, involved hand, dominant hand and characteristic of disease.4) Inclusion criteria: chronic pain in lateral zone of elbow, definite tenderness in lateral epicondylitis, age more than 15 years, and VAS score more than 6. exclusion criteria: radicular pain to the upper limbs, established Carpal Tunnel Syndrome, and past history of tennis elbow treatment. 5) Intervention: Group A will receive Corticosteroid injection (Methyl-prednisolon acetate 1 ml) single dose into the painfull zone, Group B will receive a local anesthesia (procaine 2% 1 ml). 6) Main outcome measures: primary outcome is Survey of the elbow inability level measured with DASH questionnaire and secondary outcome is pain score that measured with VAS questionnaire.