At present, about 300 patients with thalassemia major are living in Germany. Starting in 1991, a multicenter study in Germany has concentrated on identifying all patients suffering from thalassemia as well as on establishing a uniform therapy protocol including follow-up diagnostic procedures. After six years of study, the data of 198 patients suffering from thalassaemia major were analysed. The majority of these patients originate from endemic regions around the Mediterranean Sea. The patient's median age is 13.8 years (range 1-37.5 yrs.). At present, about 20% of patients are older than 21 years. Regarding transfusion therapy, a shortening of the average transfusion interval to 3 weeks in most cases occurred. Throughout the entire period, median baseline haemoglobin concentrations of 10.0 g/dl could be observed. The evaluation of serum ferritin levels revealed considerable differences depending on patients age. 60% of patients in the first decade of life showed good therapeutic results with serum ferritin levels below 1800 ng/ml. In contrast, 52% of patients older than ten years presented with ferritin levels above 2500 ng/ml. During the observation, a decreasing number of patients with ferritin levels above 2500 ng/ml was observed in patients aged 15 to 21 years of age. The situation of patients aged 9 to 15 years proved to be more problematic. More than half of all treated patients presented with siderotic complications as cardiac disease in 13%, liver disease in 21%, impaired glucose metabolism in 14%, hypothyroidism in 24% and hypogonadism in 59% of all patients. These values did not change considerably during the observation apart from an increase of cardiac disorders to 20%. Since the situation concerning siderosis and the lack of compliance proved to be particularly difficult in adolescent patients, further efforts has to concentrate on this age group.