The rising incidence of sexually transmitted infections (STIs) provides a challenge to clinicians in all fields to whom patients may present. This chapter aims to provide an overview of the common infections, particularly those aspects which may be relevant to urologists. There have been many recent changes in diagnostic testing (including use of polymerase chain reaction DNA identification) and treatment for STIs, especially with regard to the increasing resistance of gonorrhoea to many antibiotics. The presence of sexual infection is often overlooked in clinical practice or diagnosed late in the course of investigation of symptoms, resulting in difficulty in treatment and in some cases permanent sequelae. This overview should enable urologists to consider STI when formulating a list of differential diagnoses and aid appropriate testing or prompt referral to specialist genitourinary medicine clinics.