New mobile computing devices including smartphones and tablet computers have emerged to facilitate data collection in realtime at the point-of-care. Earlier, we developed a web based Childhood Obesity Informatics System (CHOIS) and deployed it for obesity surveillance by the Illinois Department of Public Health (IDPH). In the process, a school nurse collects data on an individual's height and weight for determining Body-Mass-Index (BMI), which is conventionally used for determining at-risk and obese patients. However, this process is often limited by the internet access at the site. This paper describes a solution by demonstrating a smartphone-based mobile application, mCHOIS. The application developed in this project enables a field worker to input or modify the data and store it locally in the phone. Once internet connection is available either through the broadband or through the built-in wifi, data can be sent to the remote database of CHOIS. Updating the data and visualization of the report are also available through the phone's browser. This application has been successfully field tested and is now under deployment for use by the Illinois Department of Human Services (IDHS) for its School Health Program.