ABSTRACT Primary hyperoxaluria type I is a rare inborn error of metabolism caused by a deficiency of a liver-specific peroxisomal enzyme. It manifests by increased oxalate production that ultimately results in kidney failure, due to urolithiasis and nephrocalcinosis, and finally induces systemic oxalosis and risk of premature death. Primary hyperoxaluria type 2 is mainly responsible of urolithiasis. Enteric hyperoxaluria is a commonly seen adverse event of Crohn disease or after extensive intestinal resection. These affections represent the main etiologies of massive hyperoxaluria. If not recognized very soon and adequately treated, these conditions can progress rapidly to end stage renal failure.