Introduction: The aim of this study was to identify the factors arising from (i) personal perception of the vaccine or (ii) the mother's social environment and entourage that are associated with vaccination dropout in children aged 12 to 23 months. Materials and Methods: A cross-sectional observational study was conducted from 25 October 2022 to 18 February 2023 among mothers of 336 children aged 12 to 23 months in Kisangani. A pre-tested and administered questionnaire was used to collect data based on three-stage cluster sampling. Analyses were performed on STATA 13 using stepwise logistic regression with a threshold of 0.05. Results : After adjustment by multivariate logistic regression, the following factors were significantly associated with discontinuation of BCG vaccination in children aged 12 to 23 months: mother's religion (ORa=2.1 [95% CI : 1.1 - 4.4]), ignorance of vaccination schedule (ORa= 3 [95% CI :1.4 - 6.7]), not being informed by vaccinators to allay fears (ORa= 2.5 [95% CI :1.2 - 5.4]) and refusal to vaccinate one's child if the incidence of the disease decreases (ORa= 2.9 [95% CI :1.3 - 6.5]). Conclusion: In Kisangani, mothers' access to information and knowledge about routine vaccination were limited, with low BCG vaccination coverage. There is a need to increase awareness among mothers and carers in order to improve their knowledge of routine immunisation.