Rupture of the fornix renalis, a special form of obstructive nephropathy that receives too little attention as a separate entity, is reintegrated into urological thinking, with a fuller description of the pathophysiology, morphology and clinical course than has previously been given. Overloading (iatrogenic mainly) of the lymphatic and venous system of the kidney caused by excessive pressure is usually implicated, affecting the renal parenchyma, the renal sinus and Gerota's fascia. Rupture of the calyceal fornix renalis functions partly as a self-help mechanism. Measurement of the urovascular diversions of urine caused by obstruction is not yet possible. Clinical observation and experimental reproduction give predominantly corresponding results. Schematics make the text easier to understand. Recent ureteroscopic techniques are introduced to bring the topic up to date.