The kidney is particularly susceptible to the deleterious effects of drugs, and drug-induced nephropathies are now fairly well understood. All the components of the renal parenchyma can be affected, but we have focused our attention on tubulointerstitial nephropathies. All of the pathophysiological mechanisms are not known, but it is possible to describe two types of renal alteration. The first is due to a direct toxic action by, for example, antibiotics, contrast media, nonsteroidal antiinflammatory agents, antalgics and analgesics. The second type of alteration appears to be due to immunoallergic reactions to, for instance, penicillin and its derivatives, rifampin, sulphonamides and phenindione. We also underline the risk factors that favour the occurrence of renal complications and the means that can be used to prevent them.