Background and purpose: Patients with irresectable locoregional recurrent breast cancer en cuirasse (BCEC) do not have effective curative treatment options. Hyperthermia, the elevation of tumor temperature to 40–45 °C, is a well-established radio- and chemotherapy sensitizer. A total of 196 patients were treated with reirradiation and hyperthermia (reRT+HT) at two Dutch institutes from 1982–2005. The palliative effect was evaluated in terms of clinical outcome and toxicity. Patients and methods: All patients received previous irradiation to a median dose of 50 Gy. In all, 75% of patients received 1–6 treatment modalities for previous tumor recurrences. ReRT consisted of 8 × 4 Gy given twice a week or 12 × 3 Gy given four times a week. Superficial hyperthermia was added once or twice a week. Tumor area comprised ≥½ of the ipsilateral chest wall. Results: Overall clinical response rate was 72% (complete response [CR] 30%, partial response [PR] 42%, stable disease [SD] 22%, progressive disease [PD] 6%). The local progression-free rate at 1 year was 24%. Median survival was 6.9 months. Forty-three percent of our patients with CR, PR, SD after treatment remained infield progression-free until death or last follow-up. Acute ≥grade 3 toxicity occurred in 33% of patients, while late ≥grade 3 toxicity was recorded in 14% of patients. Tumor ulceration prior to treatment had a negative impact on both clinical outcome and toxicity. Conclusion: ReRT+HT provides sustainable palliative tumor control, despite refractory, extensive tumor growth. Compared to currently available systemic treatment options, reRT+HT is more effective with less toxicity.