The purpose of this study was to evaluate the activity and safety of OSI-211, the liposomal form of lurtotecan, in patients ineligible for curative surgery or radiotherapy and with metastatic/locoregional recurrent squamous cell carcinoma of the head and neck (SCCHN) and target lesions either within a previously irradiated field ("within") or outside a previously irradiated field ("outside"). OSI-211 was given intravenously over 30 min on days 1 and 8 at 2.4 mg/m2/day, repeated every 21 days (1 cycle). From July 2001 to March 2002, 32 patients from 14 institutions were enrolled in the "within" arm and 18 in the "outside" arm. In the "within" arm, two patients were ineligible because their tumour site was not allowed in the protocol (nasopharynx, skin) and two other patients never started treatment. Of the 46 eligible patients who started treatment, there was one objective response (response rate: 2.2% (95% Confidence Interval (CI): [0-11.5%]). Twelve patients in the "within" arm and 6 in the "outside" arm had stable disease, with a median duration of 18 weeks, 95% CI (12.7-25.7). The median time to progression was 6 weeks (95%CI: [5.9-12.7] weeks). Haematological toxicity was moderate in both arms. The most common haematological toxicity was grade 1-2 anaemia in 79% of patients. Non-haematological toxicity was mild in both arms. The most common grade 3-4 non-haematological toxicity was infection in 8.5% of patients. OSI-211 administered on d1 and d8, every 3 weeks, is well tolerated, but shows only minimal activity in locally advanced/metastatic SCCHN.