Central venous line placement is a standard procedure in critical care and peri-operative medicine. This procedure can be associated with severe complications. In contrast to the landmark technique, ultrasound-guided punctures can significantly reduce the rate of complications. Patients with a high risk for difficult vascular access include critical care and emergency patients as well as patients on anticoagulation medication and dialysis. Placement of central venous catheters can be difficult in ventilated patients and if there has been prior surgery in the puncture area. In children and small infants central venous access can also be challenging due to the anatomical relationship in the head and neck region. Puncture techniques are explained briefly by means of ultrasound anatomy. Typical ultrasonographic images visualize pathological findings in order to identify dangers and complications in central venous catheterization.