The arrival of new cephalosporins faces the clinician with an evergrowing confusion as to the drug of choice. The older agents (cephalexin, cephradine, cefadroxil and cefaclor) and the newer formulations cefatrizine and cefuroxime axetil are intensively used for treatment of mild and moderate infections. The oldest agents have a better pharmacokinetic profile but are less active against Gram-positives and Gram-negatives. Cefaclor, cefatrizine and cefuroxime axetil have improved in vitro activity against H. influenzae and/or against S. aureus and M. catarrhalis. However the mean free serum concentrations after proposed standard daily doses of cefaclor (3 x 250 mg/d), cefatrizine (2 x 500 mg/d) and cefuroxime-axetil (2 x 250 mg/d) are lower than those of the older cephalosporins. In comparison amoxicillin-clavulanate is equally efficacious, has a more reliable pharmacokinetic profile and is less expensive than cefaclor and cefuroxime axetil in a comparable dose (e.g. 3 x 500 mg/d).