A total of 2,633 tennis players were investigated for the presence of elbow pain at a Southern California tennis school. Of these, 811 players (31%) had experienced elbow pain and 41% of these currently had pain. The lateral humeral epicondyle, the location of classic tennis elbow, was the most frequent site of discomfort, and the backhand was the most painful stroke among those players with lateral epicondylitis. The percentage of players with a history of elbow pain increased almost linearly from ages 21 through 25 to ages 51 through 55 and increased with increasing years of play, especially after ten years. Frequency of play was highly significant, with the incidence of pain being five times greater for individuals playing once a day than for those playing once a month. The harmful effects of tennis may be cumulative, and many variables may interact before elbow pain occurs. In the majority of players, tennis playing appeared to be a significant factor in the production of elbow symptoms. Several forms of treatment were successful, but the most successful (in 100%) was alteration of the tennis strokes.