This study was conducted to assess the microplastic contamination in blood cockle inhabiting in Thi Nai lagoon, Binh Dinh province. The cockle individuals collected from the lagoon were treated in KOH 10% to determine microplastic particles in their digestive tract. The results showed that, there were two types of microplastic in the digestive tract of the cockles, that were fibers and fragments, with total concentration of 13 particles in sunny season and 3.26 ones in rainy season. The fibers mostly had the length of from 300 to 2100 µm. The fragments was dominant in the area range of from 45,000 to 400,000 µm2. Yellow and white were the dominant colours of the fibers while white, yellow and brown were the main colours of fragments.