Background Data on testing and detection of sexually transmissible infections (STIs) in younger MSM are scarce and no specific study focusing on teenage MSM has been published. In this study we report on sexual risk behaviours and STI testing and detection in teenage MSM aged 15–20 attending a sexual health service.

Methods Data were extracted from Melbourne Sexual Health Centre’s computerised medical records system on self-reported sexual behaviours and test results between July 2008 and June 2012. Results for MSM aged 15–20 were compared with those of older MSM.

Results 445 MSM aged 15–20 and 4313 MSM aged 20 or older were included. The median number of casual male partners in the past 12 months was 4 and 5 (p = 0.015) for teenage and older MSM, respectively. Compared to older MSM, Teenage MSM were less likely to participate in insertive anal sex (91.9% vs 86.8%, p = 0.002) and more likely to participate in receptive anal sex (86.3% vs 92.4%, p = 0.002) with casual male partners. Teenage MSM were more likely to consistently use a condom in insertive anal sex (39.0% vs 32.7%, p = 0.024) with regular partners but less likely to consistently use a condom inwith receptive anal sex with casual male partners (45.5% vs 56.6%, p = 0.001).

The prevalence of rectal gonorrhoea (2.8% vs 3.5%, p = 0.472), rectal chlamydia (5.9% vs 6.8%, p = 0.496) and early syphilis (1.5% vs 2.2%, p = 0.346) were similar in the two age groups. More teenage MSM had pharyngeal gonorrhoea (4.8% vs 2.0%, p < 0.001) but more older MSM were diagnosed for urethral chlamydia (0.7% vs 3.3%, p = 0.004) and HIV (0.3% vs 1.8%, p = 0.021).

Conclusion A high level of sexual risk was seen among teenage MSM together with a high prevalence of STIs. More innovative and age-specific measures should be adopted to promote sexual health messages to younger gay men.