A patient with a unique form of large granular lymphocytosis and multiple cranial neuritis is reported. The patient presented with facial weakness, diplopia and dysarthria. An increase in large granular lymphocytes (LGLs) was seen in blood (1.8 x 10(9)/l), CSF (237/microliters) and bone marrow (20% in a normocellular bone marrow). The phenotype of the LGLs in CSF, blood and bone marrow was CD2+ CD3+ CD4+ CD8- CD16- CD56- and CD57-. The unique features of this case include the CD4+ phenotype, the relative abundance of CSF LGL and the clinical presentation.