Watch and Wait is a randomised phase III trial to determine whether initial treatment with rituximab in patients with advanced stage asymptomatic follicular lymphoma (grades 1, 2 and 3a) results in a significant delay in the initiation of chemotherapy or radiotherapy and the impact of each strategy on patient-related quality of life. 360 patients randomised to receive either Rituximab treatment and maintenance or to a Watch and Wait strategy. Samples collected for trial: Formalin fixed paraffin embedded tumour block or unstained slides (lymph node and bone marrow)- sent to HMDS. Blood and bone marrow sample taken at baseline and if patient in CR clinically and radiologically at 7, 13 and 25 months - sent to University College London Hospital.