In the past three years 42 patients with heterozygous beta-thalassemia have been observed in our clinic. This group included 39 foreign and three German patients. A ratio of the MCV and the number of erythrocytes below 14 and normal serum iron level distinguish between the hereditary anemia and iron deficiency anemia. The diagnosis is confirmed by haemoglobin electrophoresis. For recognition of the most frequent type in Europe - the heterozygous beta-thalassemia - the demonstration of an elevated HbA2 level by simple microcolumn technique is sufficient. Ten out of 42 patients have been operated because of cholelithiasis. Five additional persons revealed gall bladder stones by ultrasonography. The high incidence of 36% in relatively young patients probably is due to longstanding hemolysis, which produces usually radiolucent pigment stones. Therefore attempts to dissolve gall bladder stones in patients with thalassemia do not seem to be rewarding.