An electronic Influenza like Illness surveillance system developed to support general practices to electronically notify the cases of influenza like illness (ILI) for national sentinel surveillance in New Zealand. Content analysis was performed to capture the information necessary for ILI surveillance. An online form was implemented within the patient management system to record the details of ILI cases. A middleware framework was developed to manage the information flow between GPs and national influenza surveillance coordinators. The framework used an HL7 version 2.4 messaging standard to receive the notification data and Rhapsody integration engines to parse the message and store the information in national ILI data base. This paper presents the system design and implementation details of electronic ILI notification system. It presents data model designed to capture information for ILI case along with the HL7 messages structure implemented in the system.