Patients with major burns experience pathological changes which have been shown to influence the pharmacokinetics of antibiotics. Subsequently it has been demonstrated that conventional doses of some antibiotics given to patients with major burns may result in sub-therapeutic serum concentrations. The aim of this thesis was to identify antibiotics used to treat infection in critically ill patients with burns, and to develop dosage guidelines for those where data is lacking. A survey of antimicrobial use in burns centres in the UK was undertaken, leading to the identification of five antimicrobials to be studied further. Published pharmacokinetic values for gentamicin were used to develop dosage guidelines for extended dose administration. With vancomycin, current dose recommendations were reviewed for their appropriateness. Three more antimicrobials were identified where little or no pharmacokinetic data were available for patients with burns; meropenem, linezolid and colistin. A patient study was therefore set up where serum samples at steady state were collected from patients enabling the calculation of pharmacokinetic data. These were related to pharmacodynamic principles in order to propose dose recommendations.