This paper aims to study the impact of Marketing Information Systems (MKIS) on Decision Making Systems (DMS) at banks sectors. Islamic International Arab Bank (IIAB) managers in Jordan are the target of this study. A questionnaire was developed to achieve the study's objectives and distributed to (30) branch managers in IIAB. The questionnaire has 5 variables; four variables are used as independent variables (Databases System, Marketing research, marketing analysis, and marketing intelligence). Also, the "decision-making systems" is used as dependent variable.