Neurologic complications after allogeneic hematopoietic stem cell transplantation (HSCT) are rare but poorly understood. We present a case report of a 57-year-old-male patient who was diagnosed in 2009 with acute myeloid leukemia (AML). He received two standard induction chemotherapies, as well as a following consolidation. Six months later, an allogeneic HSCT was performed. Shortly after HSCT the patient developed progressive polyneuropathy of the lower legs and hypoesthesia. Five months later a severe dementia followed. All images of the brain and spine showed no specific pathologies. High dose corticosteroids and immunoglobulins did not improve the neurologic symptoms. Due to severe worsening of the neuropsychiatric status and the clinical presentation, chronic inflammatory demyelinating polyneuropathy (CIDP) was suspected. Therefore, the patient received ten cycles of plasmapheresis. The patient showed a significant improvement of the neuropsychiatric symptoms and cognitive status. CONCLUSIONS: Immune mediated neuropathies after allogeneic HSCT, such as CIDP, have great variability in symptoms and presentation and are challenging to diagnose and treat. Plasmapheresis is a safe and efficient treatment for patients with unclear persisting autoimmune neuropathy after HSCT.