We have developed an interactive personal computer program for teaching the antinuclear antibody (ANA) test to medical technologists. The program, called ANA-Tutor (Sanofi Diagnostics Pasteur Inc, Chaska, Minn), introduces the user to the microscope-based immunofluorescence assay for ANA and examines understanding of the test. ANA-Tutor is based on digital images of human epidermoid carcinoma cells that have been labeled with fluorescein-conjugated antibodies using a standard indirect immunofluorescence assay for ANA. The program requires minimal computer literacy and has a number of advantages over traditional approaches to teaching the ANA test.