Microplastics are a global environmental concern due to their presence in terrestrial, freshwater, and marine environments, posing risks to ecological and human health. Runoff of freshwater from the land into water ways is a known pathway to microplastic contamination of marine environments. Thus, identifying the river systems that act as local sources of microplastics to the marine environment is imperative to mitigating risks. In North Queensland, much of the land is dedicated to agriculture, mining industries, and towns which are directly connected to the inner Great Barrier Reef World Heritage Area (GBRWHA) through river mouths. In this study, we sampled surface seawater at the river mouths of seven sites along the GBRWHA, from the Tully River to the Daintree River, to gain an understanding of microplastic input into the coastal area and potentially inner reefs. Sampling events have occurred three times per year in February, June, and October since 2017 to account for seasonal differences in microplastic abundance. Samples were density-separated and vacuum-filtered onto stainless-steel meshes using established methods. Meshes were visually inspected for putative plastics using stereomicroscopy and these were then chemically confirmed using Fourier-transformed infrared spectroscopy (FT-IR). Preliminary data using samples processed from 2018 showed an average of 15.21 +/- 7.0 SD putative plastics per site. The Kurrimine River had the highest average abundance (25.8 +/- 36.82 SD) while Russell-Mulgrave River the lowest (9.16 +/- 3.87 SD). On-going sample processing and analysis will provide a unique dataset to map spatial and temporal differences in microplastic input along the GBRWHA and assist GBRWHA management initiatives.