Objective: To investigate the difficulties experienced by mothers, that influence the failure of Exclusive Breast Feeding.Method: qualitative study, exploratory and descriptive. There were semi-structured interviews with 14 women. The data treatment occurred by means of the content analysis, in the form of thematic analysis.Results: Mammary complications; negative influences of familiar; job out of home and various household duties; insufficient information and weaknesses in communication among professionals of prenatal care; insertion of artificial teats (bottles) in the hospital.