Impaired endothelial function is the initial step in atherogenesis, which is largely responsible for ischaemic heart disease and thrombotic strokes decades later.Fourty two children with first episode nephrotic syndrome (FENS) aged 1–16 years and 40 controls were enrolled. Soluble thrombomodulin (sTM), tissue plasminogen activator (t-PA), plasminogen activator inhibitor −1 (PAI-1) and von-willebrand factor (vWF) levels were measured in plasma in FENS, at 12 weeks of drug induced remission and in steroid resistant nephrotic syndrome (SRNS) patients at diagnosis.PAI-1, sTM, vWF and t-PA were significantly raised at the onset of nephrotic syndrome (p < 0.0001). All the markers had a fall after 12 weeks of steroid treatment, but were still raised. Children with SRNS had higher levels of sTM, tPA, vWF as compared to infrequent relapsers, at onset and at 4 weeks of steroid treatment.Children with idiopathic nephrotic syndrome have endothelial dysfunction which is largely dependent upon disease activity.