We present the updated British Association for Sexual Health and HIV (BASHH) guidelines for post-exposure prophylaxis (PEPSE) to HIV. This document includes a review of the current data to support the use of PEPSE, considers how to calculate the risks of infection after a potential exposure, and provides recommendations on when PEPSE would and would not be considered. We review which agents to use for PEPSE including the potential for drug-drug interactions and make recommendations for monitoring individuals receiving PEPSE. Other areas included are the possible impact on sexual behaviour, cost-effectiveness and issues relating to service provision. Throughout the document, consideration is given to the place of PEPSE within the broader context of HIV prevention strategies and sexual health.