Life of the river sustains on its flow. River systems provide many beneficial values and services, including flood mitigation, groundwater recharge, navigation, water supplies, pollution attenuation, nutrient transport and recycling, biological productivity, aesthetic values, and recreational opportunities such as fishing, boating, swimming and wildlife viewing. In-stream flow is necessary to sustain these and other utilitarian and intrinsic values. For Bangladesh being located downstream of many rivers, it is very important to care about the quantity and chemical as well as ecological quality of its river water. Germany's river Elbe originates in Czech Republic, thus the situation is comparable to the transboundary water problems Bangladesh faces. The comparative analysis of water framework directives and policy, plan of Germany and Bangladesh on maintaining the in-stream flow of rivers (Surma and Teesta rivers of Bangladesh and Elbe river of Germany) is the main focus of this paper. The study puts forward key information and recommendations to maintain the in-stream flow of river.