The available literature on the fate of nitrogen in waters and sediments is reviewed. Emphasis is placed on the importance of N to aquatic productivity, the pathways leading to N gains or losses in aquatic ecosystems, and the availability of N in sediments to the overlying waters. Important biological reactions include N mineralization and immobilization, nitrification and denitrification, and N fixation. The effect of sediment properties, lake morphology and environmental factors (pH, temperature, dissolved oxygen, oxidation‐reduction potential) on the pathways and rates of turnover are considered. The mixing process in sediments appear to be the most important in releasing sediment‐N to waters. Several facets of the N cycle in waters and sediments require further elucidation. Research needs are outlined.