The scope of research is mainly on the place of marketing information system on organisational decision making, taking GUINNESS Nigeria Plc as our case study. Various texts are reviewed and quoted in the text to get the fact of what the study is all about. Samples were taken from the population and using the random sampling techniques. Questionnaire were served to the chosen from the population samples and information generated were analysed using the percentage method, findings generated were used as the basis upon which recommendation are made.