Background: Maternal-fetal transmission is the most frequent mode of hepatitis B virus (HBV) contamination in Africa. Prevention of mother-to-child transmission (PMTCT) of hepatitis B is still poorly understood, and training of the health workers involved, such as midwives, is rare. Objective: The aim of this study was to assess the knowledge and practices of midwives prevention of HBV' mother-to-child transmission (PMTCT) in Brazzaville. Patients and Methods: This was a cross-sectional analytical study conducted in Brazzaville from June 1 to July 31, 2023. Midwives present at the time of the survey in the various Brazzaville health centers visited and who agreed to answer the questionnaire during a face-to-face interview with the investigator were included. Univariate analyses were performed using epi info7.2 software. Pearson's chi-square and Student's t-tests were used to compare proportions and means, which were significant at the 0.05 level. Results: At the end of our study, 93 midwives out of 127 agreed to take part in the study, i.e. a participa-