The rapid development of ICT in Indonesia encourages governments to implement e-government for supporting their services so they can improve their service delivery, strengthen accountability, and increase transparency. Unfortunately, there is a major drawback regarding the implementation of e-government. One of the drawbacks is that most organizations develop silos online services. This condition reflects a lack of e-government inter-organizational integrations. E-government integration among organizations or agencies is necessary to promote a more efficient process, accurate information, and seamless services, which are the objectives of the e-government itself. E-government integration is a complicated process as stakeholders need to consider and plan several factors to make it successful. This study identified the types of e-government inter-organizational integrations through a systematic literature review using the Kitchenham method. The study reveals the success factors which need to be concerned to implement e-government successfully. This study can be used as a reference by stakeholders to initiate an implementation of e-government inter-organizational integration.