Fluoroquinolones are generally well tolerated, clinically useful antimicrobials. This paper highlights rare, but potentially serious, adverse effects involving the kidney. Other antimicrobials have long been known to cause various forms of nephrotoxicity occurring as allergic interstitial nephritis, granulomatous interstitial nephritis, necrotising vasculitis, allergic tubular nephritis or a tubular necrosis. A Medline search (1985 to May 1999) of ciprofloxacin, norfloxacin, levofloxacin, ofloxacin, trovafloxacin, enoxacin, sparfloxacin, grepafloxacin, gatifloxacin, clinafloxacin and moxifloxacin was conducted to ascertain the incidence and features of fluoroquinolone nephrotoxicity. Unfortunately, the data primarily consist of case reports and temporally related events. The incidence of these adverse effects is hard to estimate, and the cause may be multifactorial. While the use of ciprofloxacin appears to increase the risk, this may be due to its longer and more widespread use when compared with the newer agents.