Background Tendon pain is common in professional athletes as well as in sedentary people. It occurs in 30% –50% of all sports related injuries. Incidence of injury has been reported in various forms. For instance, in club gymnastics injury rates vary between 2 to 4 and 39.9 per 100 school children per year.It has been found to occur in approximately 1–3% of people in studied populations. The peak incidence is in the early fifth decade and a nearly equal gender incidence is seen. Tennis elbow is seen commonly associated with obesity, smoking and physical loading during activity as well as playing tennis. Various conservative treatments are available but none of them proved to be superior in treating the condition. This study was conducted to check the efficacy of Autologous blood injection as a new treatment modality. Materials and methods A Randomized controlled trial was conducted in the Department of Physical Medicine and Rehabilitation (PMR), Regional Institute of Medical Sciences (RIMS), Imphal, Manipur for a duration of Two years (june 2018 to july 2020). All patients suffering from chronic lateral epicondylitis attending department of Physical Medicine & Rehabilitation, Regional Institute of Medical Sciences, Imphal during the study period. Results In this study, the mean improvement of VAS and PRTEE score were found to be statistically significant (p<0.05) in both the ABI and ultrasound therapy group. At 2 weeks and 3 months follow–up ultrasound therapy group shows more improvement compared to the group received ABI. But at 6 months follow–up ABI group shows more improvement of VAS and PRTEE score compared to the ultrasound therapy group and which was statistically significant. Conclusion Single dose of autologous blood injection (ABI) is superior to ultrasound therapy in the treatment of Chronic lateral epicondylitis.