We have reviewed the clinical records and the results of conservative and surgical treatment of 125 out of 172 cases of Jumper's Knee followed for at least 2 years since the onset of symptoms. All were athletes involved in various sporting activities. At follow up 15 patients had given up sport and the lesion had healed spontaneously. We used the classification of Blazina et al as modified by Roels et al. Twenty-four patients were in stage 1, 42 in stage 2, 43 in stage 3 and one in stage 4. Conservative treatment was used primarily on all patients with one exception where the tendon had ruptured. The results were very good in 42, good in 32, and poor in 43, but in 36 patients a long period of rest and reduction in sporting activity was necessary before a significant improvement was obtained. Operation was carried out on 16 patients (19 knees), 18 were in stage 3 and one in stage 4. Various surgical techniques were used. The results were very good in 7 knees, good in 5 and poor in 7. Operation is indicated after the failure of conservative measures and in patients who do not want to reduce their sporting level. The aim should be to induce healing at the bone tendon junction. We emphasize the importance of the prevention of jumper's knee in athletes.