To understand the perceptions of the effect of vaccination messages aired during the Second National Health Week in 1996 on the predisposition to vaccinate children among mothers from a lower class neighbourhood in Mexico City. 120 mothers of children between the ages of 0 and 7 years who were exposed to the campaign messages participated. They were divided into 8 focus groups based on the age of the children and level of schooling attained by the mothers. A content analysis was conducted using open-ended coding and categorization based on shared concepts. The mothers had a positive image of vaccines for the health of their children. They perceived that the messages reminded them that they needed to vaccinate their children and contributed to the mobilization of their social network in support of vaccination. The authors inferred of mother 5 narratives that some components of messages generated inaccurate interpretations and knowledge and reinforced negative attitudes and cultural and organizational barriers to vaccination in some mothers. The messages prompted the use of vaccination services during the health campaign. In the production, the form and content should be modified to overcome misunderstandings and barriers to vaccination.