IN THE PAST FEW YEARS, WITH DATA REDUNDANCY IN ENTERPRISES, AND DUE TO THE HIGH VOLUME OF DATA, MANAGERS NEED SUPPORTING SYSTEMS FOR DECISION-MAKING AND TAKING THE PROPER APPROACH. AS A RESULT, THEY HAVE DEPLOYED DIFFERENT SYSTEMS IN ORDER TO SOLVE THEIR DECISION-MAKING NEEDS. DIFFERENT FRAMEWORKS EXIST FOR CLASSIFYING DECISION SUPPORT SYSTEMS (DSS). IN RECENT YEARS, AS WELL AS INTEGRATED SYSTEMS, ENTERPRISE RESOURCE PLANNING (ERP) SYSTEMS HAVE BECOME POPULAR AND MANY ORGANIZATIONS HAVE USED THE SYSTEM FOR THEIR BUSINESS. THESE ORGANIZATIONS ARE NOW PROBABLY REQUIRED TO SELECT AN APPROPRIATE DECISION SUPPORT SYSTEM WHICH IS SUITABLE FOR BEING INTEGRATED INTO THEIR ENTERPRISE RESOURCE PLANNING SYSTEMS. IN THIS STUDY, THE EFFECT OF ENTERPRISE RESOURCE PLANNING (ERP) AND ITS EFFECT ON DECISION SUPPORT SYSTEM'S CONFIGURATION (DSS) IN THE PETROCHEMICAL COMPANY OF REGAL WERE INVESTIGATES. BASED ON THE RESULTS OF THIS STUDY, THE MATCH BETWEEN CUSTOMIZATION, AND THE ORGANIZATIONAL CULTURE, AND BUSINESS CULTURE, THE REGAL PETROCHEMICAL COMPANY CAN EXPECT DECISION SUPPORT SYSTEM TO HAVE BETTER EFFECTS ON BUSINESS OUTCOMES. ALSO, THE RESULTS DO NOT REJECT CUSTOMIZATION; RATHER, THE RESULTS SUGGEST THAT IF CUSTOMIZATION IS SUITABLE AND MANAGED PROPERLY, IT WILL YIELD EFFECTS THAT ARE IN HARMONY WITH THE DSS.