Convulsive Status Epilepticus (CSE) is the most common childhood neurological emergency. CSE is managed with anticonvulsants in a step-wise approach until seizures stop. While some management strategies for CSE are well supported by evidence, e.g. initial benzodiazepines, subsequent strategies are based on consensus not evidence. Phenytoin, the traditional second line agent for CSE has a high failure rate, causes adverse events and must be administered slowly. Levetiracetam, a newer anticonvulsant, has a favourable adverse events profile, can be administered quickly and has good efficacy for various seizure types. We propose to undertake a randomised controlled trial of second line anticonvulsants for CSE in children (phenytoin vs. levetiracetam). This multi-centre study will be a world first and have a profound impact on the management of CSE in children in New Zealand and worldwide, in either confirming the current second-line medication used or recommending a newer second-line medication.