Key populations (men who have sex with men, people who inject drugs, sex workers, trans and gender-diverse people and people in prisons) are at increased risk of and disproportionately affected by HIV, viral hepatitis and sexually transmitted infections (STIs) due to a combination of social determinants, structural barriers, poor access to prevention interventions and risk behaviours. Counselling behavioural interventions aim to change risk behaviours and are often included in key population prevention programmes. This new good practice statement reflects a lack of evidence that certain behavioural interventions have an impact on HIV, viral hepatitis and STIs in key populations. The implementation of this good practice statement may require a shift in the way service providers work and plan programmes for key populations as outlined in this document.