Having some understanding of pharmacokinetics is important for all clinicians when prescribing medications. Key elements to effective and safe prescribing include making sure that we don9t underdose a medication making it ineffective, but also do not overprescribe a treatment known to cause toxic effects. In paediatrics, there are significant physiological and developmental differences that add to the challenges of safe prescribing. This article aims to provide the clinician with some basic paediatric pharmacokinetic principles with clinical examples to aid their prescribing skills.