Background. Hyperthermia equipment produces electromagnetic energy using the frequency of 434 MHz, which through a surface cooling system (a rubber bag with a thermostat controlled liquid) allow to bring up the target tissues to therapeutic temperatures between 41°C and 45°C down to a depth of about 5 cm. The aim of our study was to evaluate the efficacy of hyperthermia in the treatment of muscle injuries, in comparison with a conventional modality like ultrasound. Methods. We enrolled 62 patients (40 males and 22 females, with mean age of 30.1±9.3 ranging between 17 and 52 years affected by acute muscular injuries of different sites and severity. Forty-three patients with a mean age of 30.5±9.9 received hyperthermia (group A) and the remaining 19 with a mean age of 28.2±8.2 (group B) ultrasound. Both groups received 8 applications, three times per week with a duration of 30' for the group(A); and 10' for the group (B). All the patients underwent a clinical examination including a pain measurement with a visual analogue scale (VAS) and a ultrasound scanner before, at the end and after one month follow-up. Results. Both groups had a significant decrease of the pain (p<0.01) even if the percentage of improvement was greater in the group treated with hyperthermia as compared with the ultrasound. In the group (A) the ultrasound scanner detected also a faster resolution of the haematoma after 2 weeks of treatment. There were neither complications nor reoccurrence at the follow-up in the group (A), while 2 reoccurrences and 1 calcification sized 2 cm occurred in a case of pectoralis major injury in group (B). Conclusions. From this preliminary study, it seems that the hyperthermia is a highly innovative, safe and reliable modality for the treatment of acute sport muscle injuries. Further research is required with prospective controlled randomized trials, adopting a placebo group and other conventional heating systems.