Preclinical management faces considerable diagnostic and therapeutic limitations. Patient history, physical examination, and few technical means (electrocardiogram [ECG], blood glucose measurement) must suffice to arrive at a suspected or definite diagnosis. Emergency treatment of most medical conditions inside the hospital differs from the preclinical setting. Critically ill patients must be transported to the hospital in emergency units with standardized equipment. Diagnosis of acute myocardial infarction relies on patient history, present symptoms, and a 12-lead ECG, and can be made with relative certainty. Therapeutic management focuses on reduction of myocardial oxygen consumption and optimizing oxygen availability. Monitoring for possible arrhythmias is essential. Few exceptional situations justify preclinical thrombolytic therapy. After a neurologic deficit has been diagnosed, the management of patients with stroke includes support of vital functions and admission to a hospital where computed tomography or magnetic resonance imaging is available. Pulmonary thromboembolism is frequently misdiagnosed even in the hospital. Preclinical physical examination, patient history, ECG, and pulse oximetry allow a positive diagnosis only in massive embolization. Anticoagulation with heparin is essential. If cardiopulmonary resuscitation is necessary, preclinical thrombolysis may be an option. Although deep vein thrombosis is difficult to recognize, classical symptoms of acute arterial occlusion are rarely missed. Treatment consists of general measures and anticoagulation.