Background: Neuroleukemiosis is a rare complication of leukemia. The diagnosis may be delayed owing to non-specific symptoms and the need for special diagnostic modalities. Case: A 70-year-old man in his sixth year of remission from acute myeloid leukemia was referred to the pain clinic for shooting and radiating pain in the left posterior leg. A lumbar spine magnetic resonance imaging showed mild disc bulging of the L2-3, which was insufficient to explain the patient’s symptoms. With insufficient pain response to lumbar epidural block and piriformis injection, we examined both sciatic nerves using an ultrasound and identified an enlarged hypoechoic mass on the left sciatic nerve at mid-thigh level. After that, we biopsied the mass under general anesthesia, and histology confirmed it to be neuroleukemiosis. Conclusions Ultrasound is an inexpensive, non-invasive, simple, and quick diagnostic modality that can be used as a screening tool in the diagnosis of neuroleukemiosis.