Polyclonal antibodies against human low-density lipoprotein (LDL), covalently coupled to Sepharose CL-4B, are used to remove LDL from the plasma of familial hypercholesterolemic patients. During a single treatment LDL-cholesterol is lowered by more than 60%, and plasma viscosity is decreased by 10%. The usual treatment frequency is once a week.The possible development of human antisheep antibodies was followed for up to 5 years. The ELISA signal rose slightly above baseline reaching a plateau within the first year. Clinically, there have been no signs of column-related adverse reactions. Due to the versatility of immunoapheresis it is also applicable to deplete IgG by coupling antihuman IgG antibodies. These columns might be indicated for patients with high panel reactivity to enable organ transplantation and for patients with autoimmune disease. In vitro tests with plasma from high-panel-reactive dialysis patients have shown that IgG could be depleted by 95% across all subclasses and that panel reactivity could be reduced from 91 to 25%.