Background: The prevalence of venous thrombosis (VT) in children with solid tumor and the role of different risk factors are not defined yet. Aim: A cross-sectional observational study was conducted to evaluate the prevalence of both symptomatic and asymptomatic catheter-associated thrombosis events in children affected with different solid tumors. Methods: Patients with a solid tumor, admitted as day-care, were consecutively enrolled over a period of 10 months. All of them had a central venous line. Physical examination, D-dimer serum tests, and eco-color-Doppler ultrasonography were performed once at any time before catheter removal. Results: Forty-two patients (14 females and 28 males)-mean age 115 months-were evaluated. Five of the 42 patients (12%) had VT. In 4 of these, VT was catheter-related: 3 asymptomatic and I symptomatic. In the last patient, VT was clinically symptomatic and not catheter related. Patients with longer duration of catheter insertion presented with a higher rate of VT (P = 0.05). Moreover, patients affected with neuroblastoma showed a higher rate of VT than the others with different solid tumors (P