The purpose of this study is to investigate the relationship between accounting information quality and customer relationship management (CRM) effectiveness. The influence of accounting information quality on marketing performance and the influence of CRM effectiveness on marketing performance are also examined. Data was collected using mailed questionnaires and the key informant of this study is marketing executives of each e-commerce company registered in the Department of Business Development in Thailand. For the hypothesis testing, ordinary least square regression is assigned as statistical technique and 89 completed questionnaires are used in the analysis. The results indicate that accounting information quality positively relates to CRM effectiveness and marketing performance. The research findings also show a positive relationship between CRM effectiveness and marketing performance. In addition, this study discovers that CRM effectiveness has a mediating effect on the relationship between accounting information quality and marketing performance.