Cases with a pathological diagnosis of renal venous thrombosis (RVT) associated with nephrotic syndrome (NS) were studied retrospectively for clinicopathological evaluation. The material consisted of 21 RVT cases which were diagnosed in 2000 consecutive pediatric necropsies, with an overall incidence of about one percent. Eight of the 21 RVT cases were associated with nephrotic syndrome (34%), and this group formed 0.4 percent of the total necropsies in our pediatric center. The glomerulopathies of these nephrotic patients consisted of three cases of Finnish-type congenital NS (FCNS), three cases of renal amyloidosis secondary to familial Mediterranean fever, and two cases of membranoproliferative glomerulonephritis (MPGN). The presence of sepsis associated with disseminated intravascular coagulation, and the morphological age of the thrombi suggested that the RVT was secondary to sepsis in the FCNS cases. In the MPGN and secondary renal amyloidosis cases, the long duration of both the nephrotic state and the administration of diuretics along with glucocorticoid treatment and also the newly formed thrombi without infarction are strong evidences, although not definite, that the RVT developed as a complication of the glomerulopathy. Even though there were no definite clinical criteria for the diagnosis of most of the RVT cases, we would like to emphasize the importance of flank pain, the rapid deterioration of renal functions in a stable nephrotic patient, as well as the hypercoagulable state in the consideration of the development of RVT which indicate the need for appropriate radiological studies for confirmation of this condition during life.