• SEXUAL NETWORKS
• SEXUAL BEHAVIOUR
• PUBLIC HEALTH

Sexual health services in the UK are under increasing financial pressure,1 so the need to ensure that those at highest risk of STIs and HIV receive appropriate care is greater than ever. While some men who have sex with men (MSM) have long been recognised as one such population group2 with well-established systems in place to identify them, others such as swingers are not, as the paper by Dukers-Muijrers et al 3 highlights. Their data from sexual health clinics in the Netherlands show how patients who, when asked, identified as swingers and/or who reported partner-swapping, having sex with other couples together with their partner or visiting sex clubs for couples, also reported other behaviours known to be important for STI/HIV transmission including larger numbers of partners, condomless sex, paid and same-sex partners.3 I emphasise ‘when asked’ as these questions were not routinely asked in one of the study clinics, meaning that many swingers there will have missed out on receiving the care they needed, with implications for their own, their partners' and public health.

So, how many swingers are there? Reliable estimates are difficult to come by, in part because swingers are a hidden population and also because swinging can be defined in various ways, as reflected by the clinics in the study by Dukers-Muijrers et al 3 asking several …