All-trans retinoic acid (ATRA) is widely used as a differentiation therapy to induce a complete remission in patients with acute promyelocytic leukemia (APL) [1]. The major adverse effect during ATRA therapy is an increase of leukocytes, which is often accompanied by retinoic acid syndrome [2]. This reaction is characterized by fever, respiratory distress, radiographic pulmonary infiltrates, pleural effusions, and weight gain [3]. It has also been reported that ATRA-associated neurological symptoms such as headache and pseudotumor cerebri [4] are mainly caused by intracranial hypertension. We describe a patient who developed multiple mononeuropathies during ATRA therapy for APL.A 23-year-old Japanese female was admitted with fever and purpura in November 1997. APL with disseminated intravascular coagulation was diagnosed. She received ATRA (45 mg/m 2 /day) with chemotherapy including daunorubicin (40 mg/m 2 /day, on days 9, 10, 21, and 22) and behenoyl cytarabine (200 mg/m 2 /day, on days 9, 10, 11, 21, 22, and 23), and supportive therapy for disseminated intravascular coagulation. She had a slight headache after administration of ATRA, but there were no findings on the neurological examination and computed tomography scan of the brain. On the seventeenth day after admission, a neurosurgical operation was performed because of acute subdural hematoma. Although ATRAassociated headache persists, no symptoms remained, which were caused by intracranial hemorrhage and operation. Furthermore, she complained of diplopia, and burning pain and contact dysaesthesiae at the dorsum of the left hand and the right foot on day 21 of the ATRA treatment. She also had weakness in the same extremities. Tendon reflexes were normal. Electrophysiologic study revealed a decrease of right peroneal nerve conduction velocity and amplitude. Although right abducens nerve palsy and visual disturbance were present, there were no papilloedema and abnormalities on magnetic resonance imaging of the brain. Lumbar puncture showed normal cerebrospinal fluid with normal pressure. She had no manifestation of autonomic disturbances. ATRA was discontinued because a complete remission was achieved on day 51 after administration of ATRA. Total dosage of ATRA was 3,390 mg. She received three times the intensive postremission chemotherapy (daunorubicin, cytarabine, mitoxantrone, mercaptopurine, and prednisolone). Symptoms of peripheral neuropathy and findings on electrophysiologic study gradually improved as well as headache and dry skin after discontinuation of ATRA, in spite of additional chemotherapy. The right abducens nerve palsy also partially improved.To the best of our knowledge, this is the first report of ATRA-induced multiple mononeuropathies. Neurological symptoms might be considered as atypical pseudotumor cerebri with focal neurological sign [5]. However, there was no evidence of intracranial hypertension. Furthermore, we carefully excluded a possibility that other medication including anticancer drugs induced peripheral neuropathy. Clinicia...