Recent studies indicate a great need for dental treatment and preventive services in dentally underserved communities in southern Africa. Geographic inaccessibility, limited financial resources, and a maldistribution of dental personnel are the main barriers to oral health care. This project describes the evolution and utilization of a unique, purpose-built, mobile dental unit (MDU). From a compact 2 x 2.5 meter box trailer, an enclosed area of 8 x 9 meters is formed by deploying a cover system housed on top of the trailer. Once deployed, the unit becomes four fully equipped dental operatories and a combined waiting and educational area, with all-weather protection. Comprehensive care is provided by dental auxiliaries. The underlying philosophy of the service is based on the primary oral health care approach. To date, the MDU has visited a wide variety of rural and urban communities where several thousand patients have been examined and treated. Assessment of the MDU indicates that it is an effective and viable alternative oral health delivery system.