The Berlin-Buch and Heidelberg centres used fast neutron therapy in bronchial carcinomas. The neutron source was a cyclotron in Berlin-Buch/Rossendorf and a d-t generator in Heidelberg. Three hundred twelve patients with inoperable bronchial carcinoma were treated with fast neutron therapy alone or in combination with photons. The results were then compared with those obtained from 594 patients treated only with photons. Altogether, 788 were treated in Berlin-Buch and 188 in Heidelberg. The results suggest that neutron therapy for bronchial carcinoma can be a good alternative in curative and palliative situations in the early stages.