Introduction The prevalence of hepatitis B is higher in populations at risk, such as people living on the street. This population is more vulnerable to several diseases, such as hepatitis B, which can be prevented by adhering to the three-dose schedule of hepatitis B vaccine. The main goal was to investigate the vaccination situation against hepatitis B in this kind of population.

Methods Cross-sectional study with quantitative approach. The research was developed at the Specialised Reference Centre for Homeless People (POP Centre). Participants were recruited through the Snowball Technique. The data were collected through the application of a form, from September to December 2016. This study was submitted and approved by the Research Ethics Committee of the Federal University of Piauí with the number of report 1,755,893.

Results Of the 58 participants, the majority, 49 (84.5%) were males. The age ranged from 21 to over 50 years old. Regarding sexual behaviour, 7 (12.1%) participants reported feeling same-sex attraction. Only 3 (5.2%) reported having a monogamous partner, and among these, 2 (3.4%) reported not using condoms with the aforementioned partner. Only 11 (19.0%) participants had a vaccine card. Of the total, 35 (60.3%) did not know how to report their vaccination status. Of the doses of hepatitis B vaccine given previously, 3 (5.2%) reported having taken two doses of vaccine. The remainder, 15 (35.9%), had not taken any dose of the vaccine. Only 3 (5.2%) reported having completed the vaccination schedule.

Conclusion Considering the low adherence to the three doses of vaccine against Hepatitis B, it is important to invest in the continuous supply of immunobiological and to expand orientation strategies regarding the importance of the complete vaccination scheme for this population.