Thrombo-embolic episodes are an uncommon but known complication of nephrotic syndrome. However, pulmonary thrombosis/thromboembolism is rare, especially in children. We describe the cases of two girls, aged 12 years, who presented with severe oedema in relapse. They had intermittent tachypnoea, and CT pulmonary angiography (CTPA) provided a less invasive and more definitive way of confirming pulmonary thrombosis/thromboembolism. They received heparin with resolution of the tachypnoea. Anticoagulation was continued for 6 months after the episode in one patient. They have been in remission for more than 1 year, and a thrombophilia screen does not indicate a predisposing tendency to the formation of clots. Pulmonary thrombosis/thromboembolism could present with subtle symptoms and needs prompt diagnosis and treatment to prevent a fatal outcome.