Introduction To determine the incidence and seroprevalence of HIV in Transgender and its association with risk behaviour at a national level. We realised a survey study where 455 Trans people were polled about demographic, cultural and behavioural aspects in 12 Argentine provinces. They received pre-HIV test counselling and realised serology. For calculating the incidence was applied the STARHS algorithm - I=(n/m+n))×(365.25/T)×100.

Results We analysed data from 441 surveyed: 152 positive cases (P), 276 negative (N) and 13 indeterminate (I); Prevalence was 34.47% (95% CI 30.04 to 39.11). 63.41% of N and 73.68% of P had used silicone injections (p=0.03). 316/441 were sexual workers (SW), 119 (37.66%) were P 187 N and 10 I. 35,4% of SW used condom with his last client. 54.01% of SW N and 64.71% of SW P used drugs with clients (p=0064). Estimated incidence HIV was 11.14 per 100 person-years (95% CI 4.98 to 20.99). The annual incidence was calculated using a window period of 170 days set for HIV-1 subtype B.

Conclusions The prevalence was similar to the reported in other Transgender populations (USA, Canada) and was greater in the subgroup of Sexual workers. Knowledge of other sexually transmitted diseases and use of silicone injections were significantly associated with the positive condition (HIV+). Vulnerability in sexual workers is associated with the increased consumption of alcohol, drugs, social discrimination and police violence.