Consensus infant feeding guidelines, which were developed by a multi‐disciplinary working group, were adopted by the Eastern Health and Social Services Board (EHSSB) N. Ireland, in 1991. Implementation of the guidelines was undertaken using a cascade approach. Implementation teams were established in each of the nine Units of Management. These teams were provided with training and extra resources to facilitate the implementation process. In 1991, prior to the implementation of the guidelines, a postal survey was undertaken to establish the knowledge of infant feeding and attitudes to breast‐feeding of health professionals working in the EHSSB area. Knowledge and attitude scales were developed for the questionnaire. The survey was repeated in 1993 to evaluate the impact and penetration of the guidelines. The penetration of the guidelines was good, 81% of respondents had read them. The knowledge of health professionals was significantly greater in 1993 than in 1991 (P<0.0001); reading the guidelines was an independent variable for knowledge score (eta2=0.20, P<0.0001). Health visitors exhibited the highest and general practitioners the lowest mean knowledge scores. Attitude scores in the 1993 survey were almost identical to those found in 1991; reading the guidelines was an independent variable for attitude score (P<0.0001), however the size of the effect was small (eta2=0.04).