We report a patient with an advanced stage low-grade small lymphocytic lymphoma who required regular drainage of malignant ascites for symptomatic relief despite intensive treatment. The administration of rituximab via the intraperitoneal route successfully controlled the ascites. The patient tolerated well with this unusual route of administration and has not required any further ascitic drainage for at least 8 months. In view of its simplicity, good tolerability and effectiveness to control recurrent ascites secondary to low-grade non-Hodgkin's lymphoma (NHL), this novel route of administration of rituximab is worth exploring.