A 40 year-old 2nd gesta pregnant woman (34.5 weeks of amenorhea) was admitted to hospital for abdominal pain and arterial hypotension which were rapidly related to a retroperitoneal haematoma due to left kidney bleeding. Emergency cesarean delivery under general anaesthesia was undertaken because of foetal distress. Exploration of the retroperitonal space after foetal extraction confirmed the presence of a large haematoma and abnormal left renal morphology. The retroperitoneal space was drained without any further intervention. Subsequently, abdominal and thoracic computerised tomographic examination showed bilateral dysplasia of the kidneys and pulmonary cysts consistent with the diagnosis of renal angiomyolipoma and pulmonary lymphangioleiomyomatosis. The case report is of interest because of the circumstances of discovery of the disease and because nephrectomy was not necessary to control the bleeding of the left kidney. Six months after the incident the patient and the child are in good condition.