Venous thromboembolic events (VTE) in children are mostly related to central venous lines (CVL), and are located in the central upper venous system. The incidence of VTE in children with CVL is significant. However, the majority of CVL-related VTE do not present with typical symptoms or are not recognized due to underlying disease. Asymptomatic VTE still cause significant venous obstruction and are associated with short-term and long-term clinical complications. Because the clinical diagnosis of CVL-related VTE is unreliable, screening by objective radiographic testing is required. In the upper venous system, ultrasound is insensitive for the VTE in the central venous system and venography is not sensitive for jugular VTE. Therefore, a combination of ultrasound and venography is required for accurate diagnosis of CVL-related VTE in the upper venous system. Whether ultrasound alone is accurate for CVL-related VTE in the lower venous system is uncertain. Magnetic resonance venography will likely prove a valid alternative for diagnosis of VTE both in the upper and lower central venous system, and may be combined with magnetic resonance pulmonary angiography to screen for pulmonary embolism.