AIMS This trial was conducted to evaluate the safety and pharmacokinetics of combretastatin A4 phosphate (CA4P) given intravenously as a single dose to Chinese patients with refractory solid tumours. METHODS Twenty-five patients were treated with single doses of CA4P according to a dose escalation scheme: 5, 10, 20, 33, 50, 65 and 85 mg m-2 infused intravenously over 30 min. RESULTS CA4P was generally well tolerated at < 65 mg m-2. Transient, moderate increases in the heart rate-corrected QT interval occurred at all doses. CA4P produced a transient dose-dependent increase in neural and gastrointestinal toxicities. Acute renal failure occurred in one dehydrated patient who had also taken paracetamol. There were seven episodes of dose-limiting toxicity at doses >= 65 mg m-2, including two episodes of reversible ataxia at 85 mg m-2. For CA4P, at 50 mg m-2, mean (SD) peak plasma concentration (C(max)) was 0.99 (0.33) mu m, area under the curve from time zero to time of last quantifiable concentration (AUC(0,t)) was 1.42 (0.30) mu m h and terminal elimination half-life (t(1/2)) was 1.81 (0.61) h. At 65 mg m-2, C(max) was 1.73 (0.62) mu m, AUC(0,t) was 3.19 (1.47) mu m h and t(1/2) was 1.90 (0.61) h. One patient with nasopharyngeal carcinoma had an obvious clinical response with central necrosis in the metastatic lung mass. CONCLUSION Doses < 65 mg m-2 given as 30 min infusions define the maximum tolerated dose in East Asian patients, and doses in the range of 50-65 mg m-2 have been selected for further studies.