The five-year follow-up results of 221 patients treated with neutrons or a neutron-boost at the West German Tumour Centre, Essen, are presented. 94 patients with gross tumour were treated with neutrons alone. 127 patients without gross tumour left behind post surgery were irradiated using a "mixed beam" schedule. The disease-free survival rate at five years is 62.6% for T1-, 71.5% for T2- and 28.7% for T3-tumours (p = 0.016). Significant differences were also found for various grades, i.e. 73.3% for G1-, 47.7% for G2- (p = 0.035) and 22.4% for G3-tumours (p = 0.024). Patients without microscopic tumour residue fared best with a survival rate of 86.6%, followed by patients with microscopic tumour (65.5%; p = 0.042) and patients with gross tumour (25.5%; p = 0.003) left behind. A functional limb was preserved in 86% of the patients with extremity lesions. The local control rate of patients with gross tumour was 76.5% compared with 53% in previous photon series. This finding underlines the potential biological advantage of neutrons in these tumours. Serious side effects ranged from 28% in the patients treated with neutrons for large volumes to 7% in patients treated with a neutron boost.