Conclusion: "Boatmen in Teknaf are an integral part of a high-risk sexual behaviour network between Myanmar and Bangladesh. They are at risk of obtaining HIV infection due to cross border mobility and unsafe sexual practices. There is an urgent need for designing interventions targeting boatmen in Teknaf to combat an impending epidemic of HIV among this group. They could be included in the serological surveillance as a vulnerable group. Interventions need to address issues on both sides of the border, other vulnerable groups, and refugees. Strong political will and cross border collaboration is mandatory for such interventions."