Context: In lateral elbow pain (LEP), it is important to improve pain, grip strength, and function. The aim of this study is to compare the effects of Instrument-Assisted Soft Tissue Mobilization (IASTM) and extracorporeal shock wave therapy (ESWT) methods on pain, grip strength, and function in LEP. Design: Randomized single-blind clinical trial. Methods: Forty-eight adults with LEP were randomly assigned to the IASTM, ESWT, and control groups. Home exercise consisting of special static stretching and eccentric strengthening exercises was given to the control group. The ESWT group received a total of 8 sessions of ESWT in addition to home exercise. The IASTM group received a total of 8 sessions of IASTM in addition to home exercise. The visual analog scale for pain, hydraulic hand dynamometer for grip strength, and Patient-Rated Tennis Elbow Evaluation scale for functionality were used for assessment. Data were collected at baseline, after intervention, and at 4-weeks postintervention. Results: At the end of the treatment and the 4-week follow-up, a decrease in pain scores and improvement in muscle strength and functionality was detected in all 3 groups (P < .001). IASTM applications were more effective than ESWT and control groups in reducing pain both after application and at follow-up (P < .001), whereas ESWT application was also effective compared with the control group (P < .001). IASTM applications were more effective than the ESWT and control groups in reducing Patient-Rated Tennis Elbow Evaluation total scores both after the applications and follow-up (P < .001). IASTM was more effective in grip strength than ESWT and control groups (P < .001). Conclusion: It was determined that IASTM and ESWT treatments were effective in reducing pain and increasing grip strength and functionality in both the short and long term in patients with LEP. It was determined that IASTM treatment was superior to ESWT treatment in reducing pain and improving grip strength and functionality.