Neurolymphomatosis (NL) is an uncommon syndrome of peripheral or cranial nerve root dysfunction secondary to infiltration by B-cell non-Hodgkin's lymphoma (NHL). A high index of suspicion is required as presenting symptoms are varied, conventional radiology has only modest sensitivity, and pathological diagnosis is often difficult. Treatment with chemotherapy alone has an objective response rate of 82%, although long-term outcomes are highly variable. This case series describes outcomes in four patients whose management incorporated PET scanning and the use of rituximab in combination with chemotherapy. PET scanning could often diagnose NL where other diagnostic modalities were non-diagnostic. Although combination therapy with rituximab and chemotherapy has been shown to be superior to chemotherapy alone in other forms of NHL, this does not appear to be the case in patients with NL. This may reflect the inability of rituximab to adequately penetrate into the central and peripheral nervous system. This is supported by the common finding that patients will relapse solely with NL despite on-going complete remission at sites outside the nervous system. The prognosis of these patients is poor, with the disease often following a progressive course despite treatment.