The pharmaceutical industry has striven for a long time to improve the cephalosporin antibiotics. Improvements have included increased potency, greater stability to bacterial β-lactamases, a broader spectrum against Gram-negative bacilli, reduced toxicity and improved pharmacokinetic properties. The injectable derivatives (with confusingly similar names) have been grouped into so-called ‘generations’. This review, prompted by the marketing of the ‘third generation’, attempts to define the roles of the cephalosporins (and the closely related cephamycins) already available or under trial.