D-penicillamine (DPA) leads to side effects in different ways: collagen and elastin crosslinking are inhibited, which results in thin and vulnerable skin, cutis laxa, elastosis perforans serpiginosa, wound healing defects and embryopathy. Toxic influences effect thrombo- and leukocytopenia (incidence 5-15%), gastrointestinal disturbances (10-30%), changes or loss of taste (5-30%), loss of hair (1-2%), and partly proteinuria (5-20%). Acute hypersensitive reactions include DPA-allergy (2-10%). Severe adverse effects are autoimmune phenomena such as pemphigus, DPA-induced lupus erythematosus, polymyositis/dermatomyositis, membranous glomerulopathy and hypersensitivity pneumonitis (like Good-pasture's syndrome) and myasthenia (all less than 1%). In addition there are a number of rare side effects, often single observations. Risk factors include a genetic disposition (especially HLA-B8 and -DR3), poor sulphoxidizers and, to a certain degree, higher age. During pregnancy and in clinically relevant disturbances of bone marrow, liver and renal function DPA is contraindicated. The total incidence of side effects amounts to 30-60%, the withdrawal rate is 20-30%; therefore clear indications and a regular survey of DPA therapy are necessary.