The objective of this randomized study was to compare a thermotherapy system, hyperthermia at 434 MHz and conventional ultrasound in the treatment of overuse sports tendinopathies. The study group consisted of 44 athletes, 33 males and 11 females (age 26 +/- 4.56 years) affected by tendinopathies at lower extremities (patellar or achilles tendons). After elucidation of the kind of trial, 22 patients were randomly assigned to hyperthermia and 22 to ultrasound. The patients received after a pain measurement and ultrasound scanning 12 treatments, 3 times a week for 4 weeks. The same standardized examination was done at the end of treatment and 1 month after the end of treatment. The assessor physician was unaware of the treatment allocation. The patients were asked to rate the ultimate outcome on the base of pain resolution and return to sports activity. Both groups had a significant decrease of symptoms (P<0.001). Hyperthermia, however, demonstrated better effects on the reduction of VAS score and on the subjective overall satisfaction (77 %) of excellent and good results in comparison to the 33 % of ultrasound. In patients with chronic overuse tendinopathies hyperthermia at 434 MHz showed encouraging results, with short-term clinical improvement, safety and no side effects.