Background Although dengue viral infections have emerged as one of the most important mosquito-borne diseases, neurological manifestations of dengue infections are uncommon. Guillain–Barré syndrome and Miller Fisher syndrome have been reported to occur as immune-mediated complications following dengue infection. We report the case of a patient who developed Miller Fisher syndrome during the acute phase of dengue fever suggesting that Miller Fisher syndrome may arise as a result of direct neurotropism of the dengue virus. Case presentation A 70-year-old Sri Lankan man with well-controlled diabetes mellitus and hypertension presented with fever of 3 days’ duration, drooping of eyelids, dysarthria, and unsteady gait. He developed bilateral asymmetric partial ptosis, complete external ophthalmoplegia, bilateral palatal palsy, unilateral tongue weakness, ataxia, and areflexia from the second day of illness. He did not have limb weakness. He had evidence of acute dengue infection including progressive thrombocytopenia and leukopenia, positive dengue non-structural protein 1 antigen, dengue immunoglobulin M antibodies, and polymerase chain reaction detection of dengue virus genome in serum. Magnetic resonance imaging of his brain and cerebrospinal fluid analysis were normal. Polymerase chain reaction for dengue virus and immunoglobulin M antibodies in cerebrospinal fluid were negative. Nerve conduction studies showed axonal neuropathy. Antibodies (immunoglobulin G, immunoglobulin M, and immunoglobulin A) against GQ1b and GT1a were negative. He was treated with intravenously administered immunoglobulins and a recommended fluid regimen for dengue fever. He made a complete recovery from dengue fever in 7 days and Miller Fisher syndrome in 20 days. Conclusions This case report highlights the rare occurrence of Miller Fisher syndrome during the acute phase of dengue fever. Neurological manifestations may occur as a consequence of direct neurotropism of dengue virus.