This study investigated the effect of the lateral counterforce armband on wrist extension and grip strength, and pain of 14 subjects with tennis elbow. Dynametric strength tests and pain analogue scale assessments were obtained on the affected and unaffected arms of subjects, while wearing the armband and without wearing the armband. Use of the armband produced parallel effects in both the affected and unaffected arms, i.e., increases in wrist extension and grip strength. The greatest effects were seen in the affected arm. There was a statistically significant increase in wrist extension strength with the armband on relative to without the armband. The increase in wrist extension strength approximately doubled the increase in grip strength for both arms, indicating the armband's greater influence on wrist extension. Although there was a low negative correlation between changes in pain and strength, it was not statistically significant. J Orthop Sports Phys Ther 1989;11(5):192-197.