Within the framework of a seven-year clinical experience on treatment of severe hyperlipoproteinemia with/without associated coronary heart disease, with therapeutic plasmapheresis (APO B-100-containing lipoprotein-apheresis), we focused the present report on two young patients aged 7 and 11 years, respectively. The older patient is a boy treated since 1990 by plasma-exchange, cascade filtration-low density lipoprotein apheresis (LDL-apheresis), and dextrane sulphate-LDL apheresis. Over the treatment period the patient was submitted to three consecutive coronary angiographies. The second is a girl first submitted to a coronary angiography and then treated with dextrane sulphate-LDL apheresis. Up to now, a total of one-hundred therapeutic plasmaphereses have been performed. The interval of treatment was of fifteen days, and a volume of 2-3000 ml of plasma was processed at each session. The systems used were the following: DIDECO Vivacell BT 798-A, DIDECO Vivacell BT 798-A + BT 803, DIDECO BT 985 (Dideco, Mirandola, Italy), KANEKA MA-01 (Kanegafuchi, Osaka, Japan). Mean (SD) plasma apo B-100-containing major lipoprotein-LDL, Lp(a)-levels during treatment, are reported below: [table: see text] The treatment was very well tolerated. Rare, moderate hypotensive events occurred. Nevertheless, all procedures were regularly completed. A mild hypochromic anemia, regressed using drug treatment, was observed in the boy. Along with the improvement of plasma atherogenic profile, a regression of skin xanthomas and unchanged favourable coronary angiograms, were obtained in the above mentioned patient.