This film presents an overview of the organization and functions of United States Army medical laboratories in the United States and overseas during World War II. The mission of the laboratories was to prevent, detect, and control epidemics, and to heal and rehabilitate the American soldier. Clinical, public health, and research laboratories are discussed. Within the army surgeon general's office, the work of fulfilling that mission was carried out among the following divisions: laboratory, epidemiology, sanitation and hygiene, venereal disease control, and training and hospital divisions. The Army Medical Department research and graduate school and the Army Institute of Pathology (now the Armed Forces Institute of Pathology) were an important part of the effort. In preparation for war, the first task was to train field and hospital laboratory units and train technical personnel. The locations of the hundreds of training and treatment facilities in the United States are shown on maps. The work of the following laboratories is outlined and their personnel, equipment, and interiors shown: service command, bacteriology, serology, veterinary (which tested animal products for human consumption), chemistry, toxicology, clinical, and histo-pathologic. After they were trained in the zone of the interior, workers were assigned to combat and communications zones. Organizational charts of army medical laboratories in combat and communications zones are shown, as are the exteriors and interiors of some of those laboratories with personnel at work. Efforts to control scrub typhus, louse-borne typhus, and malaria are outlined. The work of the Army Institute of Pathology is presented over footage of work going on in its various sections, as is the work of the Atomic Bomb Research Section and the army research and graduate school. Shots include: 8th Evacuation Hospital, Italy; 300th General Hospital, Italy; 15th Medical General Laboratory; spraying civilians to control louse-borne typhus; ditching, spraying, oiling, and dusting to control mosquitoes, spraying DDT from an airplane; tent hospitals and laboratories in Pacific jungles; 18th Medical General Laboratory, Hawaii; Antilles department headquarters laboratory, Puerto Rico.