Summary. Analbuminemia (idiopathic hypoalbuminemia) is a rare congenital anomaly of albumin characterised by very low levels of this protein. Only 21 cases have been reported in the literature. The lack of albumin is “compensated” by increased amounts of various circulating plasma proteins. Other not well understood regulatory mechanisms are responsible for the absence of severe clinical consequences. Clinical aspects, genetics and pathophysiology of this disease are discussed.