Third-generation cephalosporins have been available for the past 5 years. The continued increase in resistance of bacteria to older antimicrobial agents and the safety profile of a number of the third-generation agents have established situations in which these compounds are useful. Upper respiratory infections such as epiglottitis, lower respiratory tract infections due to Enterobacteriaceae are examples of illnesses in which third-generation cephalosporins would be preferred to older drug programmes. Bone and joint infections due to Enterobacteriaceae can be treated with thirdgeneration cephalosporins with less risk of toxicity than that associated with aminoglycoside use. But this is an area in which resistance may develop. Meningitis in the elderly due to Escherichia coli or Klebsiella pneumoniae are best treated with cefotaxime and the third-generation cephalosporins are alternative therapy for neonatal and the other forms of meningitis except Listeria or Pseudomonas . These drugs have proved extremely useful in treatment of penicillinase-producing Neisseria gonorrhoeae . Hospital-acquired urinary tract infections in the elderly can be treated with these agents since they provide excellent urinary levels and have a low risk of nephrotoxicity. The need for third-generation cephalosporins in gynaecological and intra-abdomonal infections is less clear. Selected patients will benefit from their use. Closer attention to the excellent in vitro activity and pharmacological activity of third-generation cephalosporins should establish other areas of need for these compounds; but it will be necessary to follow closely the development of resistance to these compounds since species such as Enterobacter, Serratia and Citrobacter can become resistant.