Waldenstrom's macroglobulinemia is an uncommon lymphoplasmacytic lymphoma presenting with hyperviscocity and autoimmune phenomenon. Disease is characterized by bone marrow infiltration by lymphoplasmacytic cells and raised IgM. Bone marrow morphology and immunohistochemistry is important for diagnosis. Course is indolent and anemia and age are most important prognostic factors. Treatment options include alkylating agents, anti-purine anti-metabolites, which though not curative but offer valuable responses. Newer agents like Rituximab and autologous transplant are being tried.