Oxaliplatin and 5-fluorouracil have a significant activity in locally advanced oesophageal squamous cell cancer (OSCC). However, their optimal dosage and efficacy when combined with concurrent radiotherapy as neoadjuvant treatment are unknown. This non-randomised, phase I/II study aimed to define the maximum tolerated dose (MTD) and assessed the histopathological tumour response rate to neoadjuvant oxaliplatin in weekly escalating doses (40, 45, 50 mg m(-2)) and continuous infusional 5-fluorouracil (CI-5FU; 225 mg m(-2)) plus concurrent radiotherapy. Patients had resectable OSCC. Resection was scheduled for 4-6 weeks after chemoradiotherapy. During phase I (dose escalation; n=19), weekly oxaliplatin 45 mg m(-2) plus CI-5FU 225 mg m(-2) was established as the MTD and was the recommended dosage for phase II. Oesophageal mucositis was the dose-limiting toxicity at higher doses. During phase II, histopathological responses (<10% residual tumour cells within the specimen) were observed in 10 of 16 patients (63%; 95% confidence interval: 39-82%). Overall, 16 of the 25 patients (64%) who underwent resection had a histopathological response; tumour-free resection (R0) was achieved in 80%. Neoadjuvant weekly oxaliplatin 45 mg m(-2) plus CI-5FU 225 mg m(-2) with concurrent radiotherapy provides promising histological response rates and R0 resection rates in locally advanced OSCC.