The clinical and hematological parameters of a patient described here, who inherited the genes of both hereditary elliptocytosis (HE) and beta-thalassemia, seem to reflect a mutual enhancement of the two diseases. The coexistence of the two pathologies is probably also responsible for the observed changes in spectrin: the appearance of an extra spectrin band between tetramers and dimers on denaturing gel electrophoresis and the metabolic-dependent reduction in spectrin amount. It is assumed that the instability of the skeletal network that results from the HE pathology caused increased exposure of the spectrin molecule to oxidative damage that usually occurs in thalassemic red cells. The products of such oxidation may have led to abnormal spectrin associations which finally resulted in the above changes.