Introduction: Thetennis elbow (lateralepicondylitis) isoftenseen as a diagnosis, it is reported to be present in 1% to 3% of adults. Since there is no standard protocol for the treatment of tenniselbow, the physical therapy program remains the primary treatment method. The aim of the study was to determine the effect of eccentric exercises on strengthening the hand extensor to reduce pain and increase the function in people with a tenniselbow, and to compare the effectiveness of eccentric exercises and stretching exercises in these individuals. Materials and Methods: The study included 40 patients from the Clinic for Rheumatic Diseases and Rehabilitation of University hospital Zagreb. All patients with assessed question-hand function and pain in performing concentric contraction of hand extensor and motor strength with hand dynamometer. One group conducted eccentric exercises for strengthening the hand extensor and electro procedure, and other stretching exercises and electroprocedures. Therapy was conducted over 10 days. Results: Both groups eksperienced pain reduction and increased hand function in correlation between initial and final results. ANOVA repeated measurements showed that the effect of the therapy was effective in both groups for all variables, but a significant difference in the effect of physiotherapy on the final results was confirmed in the PRTEE and DYNAMOMETER variables, with the group performing the eccentric exercise showing a better effect. Conclusion:The results indicate that this type of exercise or strengthening is effective, noninvasive and simple and could be included as a protocol for the treatment of tennis elbow.