Introduction: HaNDL (headache and neurological deficits with cerebrospinal fluid lymphocytosis) syndrome is a self-limiting benign condition which, as its name suggests, causes episodes of transient neurological deficits of a motor, sensory, aphasic and, less frequently, visual nature lasting several hours, accompanied or followed by moderate-to-severe headache and lymphocytosis of the cerebrospinal fluid. Its incidence is low in adulthood, and it is extremely uncommon in the paediatric age. Recurrence of episodes usually occurs in the first three months. It has an excellent prognosis.  Case report: A 12-year-old female with intense frontal headache that suddenly begins on the tenth day, with clinical signs and symptoms of dysarthria and right hemiparesis with subsequent aphasia and generalised hypotonia. After ruling out other conditions by means of complementary examinations and the clinical course, the patient was finally diagnosed with HaNDL syndrome, since it fulfilled the clinical criteria of the International Headache Society (IHS).  Conclusions: The patient met the criteria established by the IHS for the diagnosis of HaNDL syndrome. The main historical, epidemiological and clinical data are analysed and the differential diagnosis of HaNDL syndrome in the paediatric age is described.