Antibiotics are the most commonly administered therapy to reptiles. A logical approach to therapy is important and this encompasses quantifying the need for therapy, followed by an appropriate choice of agent. Antibiotics need to be given at an appropriate dose, frequency and route, based on current information available. It is important to keep patients at their optimal temperature (To) to maximize the effectiveness of therapy. There are three potential methods for obtaining an appropriate dosage. Firstly, an empirical dose based on experience with perceived effectiveness can be considered. Secondly, metabolic scaling can be used to estimate a likely effective dose. Thirdly, dose rates derived from pharmacokinetic studies should be considered when treating other similar reptiles. This review reports on the pharmacokinetic data that exists for antibiotics in reptiles and the spectrum of activity for each agent. The effects of the renal portal system are also briefly discussed.