Forty-six articles were included in the review. Among the studies, 52% utilised a quantitative design (n = 24), with the remaining 48% using a qualitative design (n = 22). The quantitative studies consisted of randomised controlled trials (n = 2: Arnold et al. 2019; Lauby et al. 2018), cross-sectional studies (n = 18: Bingham et al. 2013; Bowring et al. 2014a, b; Fu et al. 2018; Lemke and Weber 2017; Martin-Sanchez et al. 2020; Nebot-Garcia et al. 2022; Ooi et al. 2021; Richters et al. 2014, 2015; Santella et al. 2015; Schrimshaw et al. 2013a, 2014, 2018; Siegel and Meunier 2019; Song et al. 2013; Traeen et al. 2022; van Gemert et al. 2013), quantitative interviews (n = 4: Dodge et al. 2013; Grulich et al. 2014; Mayer et al. 2021; Ondeng’e et al. 2024), and one prospective cohort study (Dyer et al. 2015). The qualitative studies included interviews (n = 14: Baldwin et al. 2015; Bowring et al. 2015; Carrillo and Hoffman 2016, 2018; Closson et al. 2014; Copen et al. 2016; Duffin 2016; Geary et al. 2018; Ooi et al. 2022; Reback and Larkins 2013; Reback et al. 2015; Schrimshaw et al. 2013b; Silva 2017, 2018), exploratory studies (n = 6: Holloway et al. 2015; Hubach et al. 2014; Newman et al. 2016, 2018; Persson et al. 2019; Silva and Whaley 2018), and one thematic analysis (Forenza and Benoit 2016).

More than three-quarters of the studies were conducted in one of three countries: the USA (n = 24; 52.2%), Australia (n = 10; 21.7%), or Laos (n = 4; 8.7%). One study (2.2%) was conducted using participants from two countries (Germany and Austria), and one (2.2%) drawing participants from three countries (Kenya, Malawi, and South Africa) (see Table 1).

An average of 3.8 studies were published each year between 2013 and 2024 (range 0–8). The number of studies published in 2016 and 2017 declined, followed by a surge in 2018. This was followed by further declines in 2019 and 2020, with increases in 2021 and 2022. No studies included in this review were from 2023 (see Table 1).

Almost half the studies (n = 19; 41.3%) identified their population as heterosexual-identifying MSMW, including ‘behaviourally bisexual’ (n = 12), heterosexual/straight-identified MSMW (n = 5), ‘straight MSM’ (n = 1), and non-gay-identified MSMW (n = 2). Several studies referred to their population as MSM (men who have sex with men), MSMO or MSME (men who have sex with men only), MSMW (men who have sex with men and women), and MSMW-T (men who have sex with men and cis and trans women) (n = 6). Studies that focused on a subpopulation included MSMW from a racial/ethnic minority (n = 5), and attendees of sex-on-premises venues (SOPV) and/or sexual health clinics (n = 2). Four studies involved professionals from various health disciplines who work with MSMW, and the final 10 recruited participants from the general population (see Table 1 for details). None of the studies specified if their participants were cis or trans men, yet one study stated that the question was asked in their survey material (Ondeng’e et al. 2024).

Sample sizes varied considerably depending on the target populations, study length, and recruitment method. The smallest sample size was n = 10 (Silva 2018), and the largest was n = 14 774 (Martin-Sanchez et al. 2020; see Table 1 for sample sizes).

The age of participants was reported as a range, an average, a median, or a minimum age. Ages ranged from 16 (Geary et al. 2018; Grulich et al. 2014; Richters et al. 2014, 2015) to 88 (Ooi et al. 2021, 2022). The average age ranged from 25.2 (Nebot-Garcia et al. 2022) to 48.4 (Traeen et al. 2022); two studies reported a median age of 22 (Bowring et al. 2014a, b), and three studies provided a minimum age (Baldwin et al. 2015; Fu et al. 2018; van Gemert et al. 2013) (see Table 1 for participant ages).

The prevalence of men who have sex with men and women was discussed in 15 studies (32.6%) (Bingham et al. 2013; Bowring et al. 2014a, b; Dyer et al. 2015; Geary et al. 2018; Grulich et al. 2014; Lauby et al. 2018; Lemke and Weber 2017; Martin-Sanchez et al. 2020; Newman et al. 2016; Richters et al. 2015; Silva and Whaley 2018; Song et al. 2013; Traeen et al. 2022; van Gemert et al. 2013). Carrillo and Hoffman’s (2016) study reported that approximately one in 15 Australian men (6.5%) aged 16–69 years have had some same-sex experience in their lifetime, and 2% of heterosexual-identifying men have had at least one same-sex partner. According to Silva and Whaley (2018), an estimated 7.4% of American men have attractions to men and/or two or more male sexual partners. The same study reported that of the men with same-sex experience, 52.4% identify as heterosexual, and 2.6% of heterosexual men have had same-sex experiences (Silva and Whaley 2018).

Studies utilised different recruitment avenues; the majority used more than one. Baldwin et al. (2015) described the effectiveness of using an array of sampling methods to recruit participants from a ‘unique and relatively hidden population’ (p. 2017). Table 2 summarises the recruitment avenues used by the studies. Venue recruitment was the most prevalent method across commercial (n = 9) and community venues (n = 10), SOPV (n = 3), and health service agencies (n = 13). Participant referral was the second most popular recruitment method (n = 15). Three studies (6.5%) used focus groups and/or an advisory board for recruitment advice (Arnold et al. 2019; Hubach et al. 2014; Reback and Larkins 2013). Five studies (10.9%) provided participants with monetary reimbursement for their time (Bowring et al. 2015; Duffin 2016; Hubach et al. 2014; Lauby et al. 2018; Reback and Larkins 2013), and one study (2.2%) provided condoms, lubricant, and sexual health and services brochures (Bowring et al. 2015). Sampling methods included purposive, convenience, snowball, and modified chain referral.

Across 23 studies, sexual attraction, sexual behaviour, and sexual identity among MSMW were consistently shown to be related but non-congruent (Baldwin et al. 2015; Bowring et al. 2014b; Carrillo and Hoffman