The dataset comprises densities of the major crustacean zooplankton taxa collected from Loch Leven, a large shallow lake in the lowlands of Scotland, between 1972-2007. Data are provided as numbers of individuals per litre for each taxa. The data were collected by the Centre for Ecology & Hydrology and its predecessor bodies, as part of the Loch Leven long-term monitoring programme. Methods of collection varied over the period of collection with samples generally collected at fortnightly intervals. There are significant gaps in the dataset during the 1980s when funding for monitoring was limited.