 Radiotherapy is the only modality which has been proven to have curative potential in patients with localised low grade lymphoma. Despite excellent control of the local tumour, most patients relapse outside the area treated with radiation and most of these ultimately die from lymphoma. This study tests the hypothesis that the addition of six cycles of chemotherapy plus rituximab systemic chemotherapy can eradicate undetectable lymphoma deposits outside the radiation field and thereby improve the cure rate. The study will specifically test the hypothesis that six cycles of adjuvant CVP chemotherapy cyclophosphamide, vincristine, prednisolone in combination with Rituximab will improve progression-free survival for patients with stage I and II low-grade follicular lymphoma treated with involved-field radiotherapy IFRT. That is, will patients given radiotherapy plus systemic chemotherapy live longer or remain free from disease longer than patients treated with radiation alone? Radiotherapy alone is widely regarded as the standard treatment for this disease. 