ABSTRACT Background Bevacizumab, a humanized antibody to vascular endothelial growth factor (VEGF), has clinical activity against human cancer, with the addition of bevacizumab to standard chemotherapy having been found to improve outcome in patients (patients) with advanced nonsquamous non-small cell lung cancer (NSCLC). However, there have been no evidence-based studies to support the continued use of bevacizumab beyond disease progression in such patients treated with the drug in first-line therapy. We have now designed a randomized phase II trial to examine the clinical benefit and safety of continued bevacizumab treatment beyond first disease progression in patients with advanced nonsquamous NSCLC whose disease has progressed after first-line treatment with bevacizumab plus a platinum-based doublet. Methods This trial has been designed as WJOG 5910L, a multicenter, open-label, randomized, phase II trial by the West Japan Thoracic Oncology Group of docetaxel (arm A) versus docetaxel plus bevacizumab (arm B) in patients with recurrent or metatstatic nonsquamous non-small cell lung cancer whose disease has progressed after first-line treatment with bevacizumab plus a platinum-based doublet. patients in arm A will receive docetaxel at 60 mg/m2 and those in arm B will receive docetaxel at 60 mg/m2 plus bevacizumab at 15 mg/kg, with each drug administered on day 1 every 21 days until progression or unacceptable toxicity.The primary end point of the study is progression-free survival, with secondary end points including response rate, overall survival, and safety, for patients treated in either arm. Up to now, 42 patients out of the 100 planned have been enrolled in 17 centers.