<p>Unlike many common pollutants, the analysis of microplastics is challenging because these contaminants are macromolecular, they have very different size and composition, and they occur in the environment associated with other matter. Here, we review the extraction of microplastics and nanoplastics from marine organisms, with emphasis on standardization and optimization of extraction protocols. Most methods involve digesting the organic material of the organism tissue, thus leaving behind the plastic particles, which are then separated and identified. Alkali treatment has shown high recovery rates, often above 95%. Recovery might be improved by combination with other treatments, e.g. using surfactants and enzymes. Low digestion temperature is suggested to prevent plastic degradation and low-pressure filtration to avoid loss of microfibers and small particles. Detection is preferred by Fourier transform infrared and Raman spectroscopy. Scanning electron microscopy allows physical characterization at the nanoscale. We also discuss the relevance of the use of ‘microplastic’ and ‘nanoplastic’ terminologies, and propose a novel size-based nomenclature.</p>