ABSTRACT: Detritus derived from macroalgae often accumulates in the littoral and sublittoral of temperate shores. Experiments were conducted to test the hypothesis that macroalgal detritus is a source of transparent exopolymer particles (TEP). Macroalgaldetritus was incubated in artificial seawater media under various experimental conditions. TEP concentrations were found to be proportional to the concentration of macroalgal detritus; however, dissolved carbohydrate concentrations were not related todetritus concentration. As TEP concentration did not increase over time, it was probably washed off the detritus when it was initially placed in the media. However, higher concentrations of TEP (262 µg Gum Xanthan equivalent [gdetritus]^-1) were produced if inorganic nutrients were added to the media compared to controls (75 µg Gum Xanthan equivalent [g detritus]^-1). Dissolved carbohydrate and TEP concentrations increased with incubationtemperature. TEP did not form abiotically from carbohydrate precursors derived from macroalgal detritus, indicating that microbial activity was important in their formation. TEP from macroalgal detritus will result in a flux of small, sticky particlesinto the water column which may subsequently affect the aggregation of both biotic and abiotic particles. This will affect both biogeochemical nutrient cycling in coastal waters and food web dynamics.