Niemann–Pick disease type C (NPC) is an autosomal recessive neurovisceral lysosomal lipid storage disorder that leads to variable symptoms that include cognitive decline, ataxia, dystonia, cataplexy, vertical supranuclear gaze palsy, and seizures. Currently, there is no specific treatment for NPC other than palliative care. Substrate reduction therapy represents a potential strategy for treating this debilitating neurodegenerative disorder. Miglustat (Zavesca) is a reversible inhibitor of the enzyme glucosylceramide synthase, which catalyses the first step in the biosynthesis of most glycosphingolipids. Miglustat has pharmacokinetic properties that allow it to cross the blood–brain barrier, thus making it a potential therapeutic agent for treating neurological symptoms in NPC patients. We present here a case report of a Brazilian child treated with miglustat. Before treatment, the patient presented with difficulties walking and swallowing, slurred speech, moderate cognitive impairments, ataxia, ptosis, and vertical supranuclear ophthalmoplegia. On a disability scale, the patient obtained a score of 15 before treatment and 8 after treatment. Following 12 months of treatment, the patient remained stable with improvements in speech, ptosis, ophthalmoplegia, ataxia, hypotonia and seizures. The Child Behavior Checklist (CBCL) was used to assess psychopathological, behavioural and social problems before and after treatment. The CBCL showed that indices for depression, affective and attention problems were all in the normal range following treatment. Thus, for this individual miglustat was an effective, well-tolerated and efficacious medication for treatment of NPC symptoms. Follow-up maintenance studies are vital to establish whether both the efficacy and safety of miglustat persist with time.