Fast neutron therapy for locally advanced or radioresistant malignant tumors was started in November 1975 at the National Institute of Radiological Sciences (NIRS), Chiba, Japan. To evaluate the effectiveness of fast neutron therapy, mixed neutron-photon fractionated irradiation, on squamous cell carcinoma of the uterine cervix, 98 patients with Stage IIIb disease were examined to study the correlation between local control rate and histological types. The local control rate after neutron-mixed beam therapy was 73%, which decreased to 66% with photon irradiation. The five year survival rate was 49% for patients receiving neutron therapy and 49% for those receiving photon therapy. There was no statistical significance between neutron and photon therapy; we then attempted to analyze histological types to check for any gain using neutron therapy. This study was a nonrandomized trial. The preliminary results however, gave us useful information for the next of neutron therapy.