Used alone, the most recently developed cephalosporins are remarkable for their effectiveness and safety. They have a low incidence of relevant nephrotoxicity. All cephalosporins are thought to be potentially nephrotoxic at high doses, and the usual site of damage is the renal tubule. Interstitial nephritis would appear to be much less common. The pathogenesis of nephrotoxicity is therefore thought to be directly dose-related rather than due to hypersensitivity. It is prudent that this be considered when new cephalosporins are evaluated and when the clinician prescribes a cephalosporin, especially when renal function is already compromised.