We introduce the concept of a Medical Informatics Workup performed by fourth year medical students working in a busy inner-city Emergency Room. These students use portable computers (Macintosh PowerBook 170s connected to a removable cartridge hard drive and CD-ROM drive) to do the patient workups. The PowerBook 170 contains the automated medical record entry software (IMR-E), five expert system software packages, and a program that allows the PowerBook to emulate a PC-compatible computer. With this configuration the student has a portable system that allows for the creation of a computerized medical record at the patient's bedside, along with the ability to analyze the data and generate a list of differential diagnoses.