AbstractChemical components of seaweeds—carbohydrates, proteins and low molecular weight nitrogenous compounds, minerals, lipids, vitamins, volatile compounds, and pigments—are reviewed in relation to potential food uses. The nutritive values of seaweeds are briefly discussed. Bioactive compounds found in seaweeds are also discussed for pharmaceutical uses or toxicity. Finally, practical uses of seaweeds as food in Japan are described.