Ataxia in macroglobulinemia has been attributed to cerebral infarction and blood hyperviscosity, but no previous case reports documented gradually progressive cerebellar signs without these concomitants and with regression on therapy. Hematologically "benign" macroglobulinemia should be part of the differential diagnosis in patients with unexplained progressive ataxia, and may respond to treatment that would otherwise not be prescribed. There is a possible relationship between the pathogenesis of this disorder and other hereditary ataxia or dysgammaglobulinemia syndromes; methods of treatment should be investigated for possible overlap.