A prospective study was done of the results of lateral release of the common extensor origin in sixty-three patients who had a tennis elbow. Fifty-seven of these patients were followed for a mean of fifty-nine months (range, fifty to sixty-five months). At the time of the operation, the extensor origin was macroscopically normal in all but six patients. Forty-seven (76 per cent) of the sixty-two patients who were evaluated at one year had no pain or only slight pain, whereas before the operation three patients (5 per cent) had had slight pain and sixty (95 per cent), severe pain. Of the fifty-seven patients who were re-examined after five years, fifty-two (91 per cent) had no pain or only slight pain. At one year, twenty patients (32 per cent) had an excellent over-all result; twenty-three (37 per cent), a good result; twelve (19 per cent), a fair result; and seven (11 per cent), a poor result. At five years, there were thirty-two excellent results (56 per cent), nineteen good results (33 per cent), four fair results (7 per cent), and two poor results (4 per cent). No association between the preoperative findings and the results of the operation was found. It was concluded that lateral extensor release, a relatively simple operation that can be performed in an outpatient setting, may be regarded at this time as the operative procedure with which other operations for tennis elbow should be compared.