[en] The neutron therapy facility based on the cyclotron installed in the Institute of Nuclear Physics in Krakow, Poland, is described. Fast neutrons are produced by bombarding a beryllium target with 12.5 MeV deuterons. The unit has been used for treatment of cancer patients by the medical team of the Institute of Oncology in Krakow since September, 1978. Fifty-three patients were treated; most of these patients had advanced head and neck cancer. On the basis of the radiobiological experiments, a standard tumor dose of 1320 rad in 20 fractions over 4 weeks were establised. From among 34 patients with advanced head and neck cancer, treated with neutrons only, and observed for at least one year, 10 patients, (29%) are living free of cancer