Five per cent of patients with primary Sjogren's syndrome (pSS) develop malignant non-Hodgkin's lymphoma (NHL), usually of the mucosa-associated lymphoid tissue (MALT) and most frequently located in the major salivary glands. Rituximab (RTX), a chimeric monoclonal antibody against the CD20 molecule expressed on the surface of mature B cells that has been approved for the treatment of NHL, has been used to treat pSS-associated lymphoma. We have described two cases: one with MALT lymphoma in the parotid glands and the other with a rare thymus lymphoma accompanied by the rare complication of a bullous pneumopathy. Both were treated with RTX at haematological doses, which was unsuccessful in the patient with a salivary lymphoma; in the case of the patient with a thymus lymphoma, the mediastinum mass disappeared and did not relapse. Both patients experienced an improvement in the subjective symptoms of dryness, and their Schirmer's test and scialoscintigraphy results stabilised. The pulmonary bullae remained unchanged.