We report a family with a new pyruvate kinase (PK) variant in which leg ulcers have been present in four of the five affected homozygous family members, but not in any of the unaffected individuals. The propositus, an 18-yr-old boy, suffered from recurrent crises of hemolytic anemia and leg ulcers. A splenectomy was performed and the leg ulcer was treated un-successfully with a pinch graft. Studies ondialyzed hemolysates showed that the enzyme was kinetically abnorma, being almost entirely resistant to activation by fructose diphosphate. THE THERMOSTABILITY OF THE ENZYME WAS MODERATELY DECREASED, AND THE ELECTROPHORETIC MOBILITY WAS NORMAL. One may speculate that the development of leg ulcers in some kinships with PK deficiency may be related to variants of PK which exert unusual effects on the rheologic properties of the red cell in vivo.