We report the results of a short-term experiment testing the effects of microplastics (MP) on the larvae of the cold-water coral Desmophyllum pertusum (syn. Lophelia pertusa). The experiment was conducted at the Tjärnö Marine Laboratory Facilities (University of Gothenburg, Sweden). To simulate MP pollution, we used 6 μm yellow-green fluorescent polystyrene microbeads (catalog no: 17156, Polysciences). The experimental design consisted of three treatments: control treatment with (1) no MP addition (0 MP/mL), (2) addition of 1000 pristine MP/mL, and (3) addition of 1000 biofouled MP/mL. Larvae were exposed to the different treatments in 75 mL culture flasks mounted on a rotating plankton wheel to keep sediments in suspension. After a 24-hour period, the potential impact of MP on larval swimming speed was analyzed using image analysis software (Meijering et al. 2012).