We report on a case of a 17-year-old female with systemic lupus erythematosus (SLE), with a clinical history of complex partial seizure, who developed a tonicoclonic crisis after receiving hydroxychloroquine for 2 weeks at a dosage of 200 mg/day (5 mg/kg). The absence of previous similar episodes and of recurrences after withdrawal of the drug in subsequent months, the short latency after administration and the favourable short-term evolution raised suspicions for a potential role of the drug in the development of the isolated convulsive crisis. It is possible for hydroxychloroquine to be responsible for tonicoclonic seizures in predisposed subjects.