The aim of the trial is to compare the response, duration of pain relief and time to achieve pain relief after pain therapy (PT) with or without hyperthermia (mEHT) in patients with painful bony metastases. Cancer patients with bony metastases and a VAS score of ≥5 on a 0– 10 scale were treated with fentanyl patches (100 μg every three days) and zoledronic acid (4mg every 28 days) combined with mEHT (PT + mEHT) versus PT alone. Hyperthermia was performed using the Oncotherm EHY2000 plus device with the maintenance of the target temperature for 60 minutes twice a week for 2 weeks. The primary endpoint was VAS = 0–2 after treatment and an ECOG performance status reduction of at least one point from baseline evaluation. The study included 19 patients: 10 in the PT + mEHT group and 9 patients in the PT-alone group. The average age of the patients was 57 years (range 40–86). The median VAS for the PT + mEHT group was 8 at baseline and had decreased to 3, 1 and 2 at 1, 3 and 6 months after the start of mEHT respectively. The median VAS for the PT-alone group was 8 at baseline and was unchanged at the subsequent time points. The median ECOG of the PT + mEHT group was 2 at baseline and had decreased to 1, 1 and 0 at 1, 3 and 6 months after the start of mEHT respectively. The median ECOG for the PT-alone group was 2 at baseline and was unchanged at the subsequent time points. The addition of mEHT to PT significantly increases the pain control rate and ECOG compared to RT alone for painful bony metastases.