We report the details of a prospective, randomized, double-blind study that was undertaken to analyze the short-term and long-term effects of the local injection of methylprednisolone to treat medial epicondylitis. Fifty-eight patients (sixty elbows) were assigned to receive a single injection of 1 per cent lidocaine with either forty milligrams of methylprednisolone (experimental group) or saline solution (control group); both groups were also managed with physical therapy and the use of non-steroidal anti-inflammatory drugs. The two groups were not significantly different with regard to the age and gender of the patients, the duration of the symptoms, the degree of pain before the injection, or the number of dominant upper limbs involved. Six weeks after the injection, the experimental group had significantly less pain than the control group (p < 0.03), as determined with a modification of the grading system of Nirschl and Pettrone. However, the groups did not differ with regard to pain at three months and at one year. The intensity of pain, as measured on a visual-analog scale, did not differ between the two groups six weeks and one year after the injection. We believe that the improvement observed in both groups primarily reflects the natural history of the disorder, and we conclude that the local injection of steroids provides only short-term benefits in the treatment of medial epicondylitis.