Objectives The objective of the study is to assess the determinants of the low practice, knowledge and attitudes of breastfeeding mothers in the Talangaï district of Congo.Study design An analytical knowledge, attitudes and practice (KAP) study about EBF in mothers of children aged 0-6 months was conducted.Methods A KAP analytical study was carried out from December 3, 2017, to July 15, 2018, based on the four health centers of the Talangaï health district in Congo Brazzaville. Using formula from Wayne W. Daniel, 357 mothers were included. The practice of EBF was determined based on a 24-h recall. The main variables studied were the socio-demographic characteristics of the mothers and their knowledge, attitudes and practices regarding EBF based on WHO recommendations. A logistic regression analysis was performed, and the odds ratio was calculated with a 95% confidence interval.Results The mean age was 26.8 years (± 5.9 years). Mothers with 2-3 children represented 42.6% of the sample. The prevalence of EBF among infants 0–6 months old was 33.9%. Mothers' knowledge, attitudes and practices were unsatisfactory (78.4%), favourable (79.5%) and bad (67.2%), respectively. Factors associated with satisfactory knowledge were being a public official [OR: 3.18 (1.39-7.28)] and/or multiparous [OR: 2.25 (1.23-4.11)]. Mothers who had satisfactory knowledge had a higher rating of having good practices on EBF.Conclusions Factors related to good knowledge among mothers are multiparity, age and being a civil servant. Promoters’ EBF must target mothers in all sectors of activity and even in the community by sensitizing them on the subject.