Microplastics have been found in all hemispheres of the world. However, studies on microplastics are mainly conducted in Europe, North America, and East Asia. Few studies are reported in the Southeast Asian region, where a large number of plastic waste is disposed of improperly into the water. This study investigated the abundance and characteristics of microplastics in the surface water of the Chao Phraya River (Thailand), Citarum River (Indonesia), and Saigon River (Viet Nam). Samples were collected at urban and estuary zones of these rivers. The numbers of microplastics at the urban zones were 80±60, 12±6, and 68±20 items/m3 at the Chao Phraya, Citarum, and Saigon River, respectively. At the estuary zones, the numbers of microplastics were 48±8, 0±0 (0.08±0), and 42±5 items/m3 at the Chao Phraya, Citarum, and Saigon River, respectively. Microplastics with morphologies of fragments and fibres were mainly found in the rivers. Polypropylene and polyethylene particles were the most abundant in all collected samples. Since the selected rivers play important roles in water supply and aquaculture activities, the presence of microplastics in these rivers may negatively impact aquaculture and human health. Potential plastic management strategies to minimize microplastic problems in the selected rivers were also proposed in this study.