Study aim: Main Goal: Compare the effectiveness of corticosteroid injection vs. electroacupuncture in managing pain and function in tennis elbow patients. Secondary Goals: Measure pain and function changes before and after treatment (3 and 6 months) using VAS and PRTEE. Compare outcomes between the two treatment groups. Practical Goal: Identify the more effective method to improve patient care and update clinical guidelines. Design: Participants will be randomly assigned to one of two groups: the corticosteroid group or the electroacupuncture group. The required sample size is 22 participants per group, totaling 44 participants in the study. Settings and conduct: This study will be a single-blind, parallel-group RCT with two treatment arms The trial will be conducted at Firouzgar Hospital, Shafa Yahyaian Hospital, and Rasoul Akram Hospital. Participants/Inclusion and exclusion criteria: Inclusion Criteria: Adults aged between 18 and 65 years. Clinically diagnosed with lateral epicondylitis (tennis elbow) for at least 6 weeks. Experiencing pain that has not responded to conservative treatments such as rest or physiotherapy. A baseline pain score of ≥ 4 on the Visual Analogue Scale (VAS). Ability to provide informed consent. Exclusion Criteria: History of corticosteroid injection or electroacupuncture for lateral epicondylitis within the past 6 months. Presence of systemic inflammatory conditions (e.g., rheumatoid arthritis). History of elbow surgery. Pregnant or breastfeeding women. Patients receiving anticoagulant therapy or with known bleeding disorders. Intervention groups: Participants will be randomly assigned to one of two treatment groups: 1. Corticosteroid Injection Group 2. Electroacupuncture Group Main outcome variables: Pain reduction and improvement of quality of life in patients with tennis elbow.