Health Protection Agency data in 2011 have revealed another increase in diagnoses of sexually transmitted infections (STIs) of 2% in the UK, with nearly 247 000 new cases, which reverses a small decline in the previous year. Increased rates are partly due to increased rates of STI testing and better tests. Gonorrhoea, genital warts, herpes, chlamydia, and syphilis all rose in incidence, especially among young heterosexual adults aged 15–24 years and men who have sex with men, who continue to have the highest risk. The data also include the incidence of infestation with the ectoparasites pubic lice and scabies mites, which present in genitourinary medicine clinics; however, these conditions may also present in primary care and other settings where healthcare providers may also have an opportunity to screen for concurrent STIs. In this article, factors associated with infestation and STIs are discussed.