© 2014, Japanese Society of Nephrology.Background: The aim of this study was to describe the incidence and contributory risk factors for thromboembolic complications in children with nephrotic syndrome (NS) and thrombosis. Methods: Among 188 children with the diagnosis of NS (80 girls; mean age: 12.6 ± 5.4 years) followed up in our hospital for the last 5 years, 17 (9.0 %) children (16 boys) identified as having thromboembolic complications. All 17 children with NS and thrombosis were screened for laboratory risk factors for thrombosis. The diagnosis was confirmed by cranial magnetic resonance imaging, doppler ultrasonography, and echocardiography. Results: Among 17 children with thrombosis, 14 (82.3 %) were found to have focal segmental glomerulosclerosis (FSGS) as underlying pathology by renal biopsy. The mean age of the thrombotic children was 4.5 ± 3.2 years at the diagnosis of NS and that was 7.1 ± 4.9 years at the time of thrombosis. The mean time from NS diagnosis to the first thrombosis development was 2.6 ± 2.3 years. Thrombosis occurred during the first year of NS in 9/17 (52.9 %) children. Most of the children (88.2 %) had venous thrombosis. Among the screened risk factors, high factor VIII level (64.7 %) was the leading factor followed by decreased antithrombin III level (29.4 %). Furthermore, 4 children had central venous catheters and 2 had infection as clinical risk factors for thrombosis. Conclusion: In this case series, subtype of FSGS, active disease state of NS, central venous catheters, and some inherited and acquired thrombotic risk factors have been identified as contributory factors for the development of thrombosis in children with NS.