Objectives: To develop and implement a collective web-based system to monitor child growth in order to study children with malnutrition. Method: The system was developed using prototyping system development methodology. The implementation was carried out using open-source technologies that include Apache Web Server, PHP scripting, and MySQL database management system. There were four datasets collected by the system: demographic data, measurement data, parent data, and food program data. The system was designed to be used by two groups of users, the clinics and the researchers. Results: The Growth Monitor System was successfully developed and used for the study, "Geoinformation System (GIS) and Remote Sensing in Mapping of Children with Malnutrition." Data collection was implemented in public clinics from two districts in the state of Kelantan, Malaysia. Conclusions: The development of an integrated web-based system, Growth Monitor, for the study of children with malnutrition has been achieved. This system can be expanded to new partners who are involved in the study of children with malnutrition in other parts of Malaysia as well as other countries. (c) 2008 Elsevier Ireland Ltd. All rights reserved.