Between April and July 1980, four zooplankton surveillance cruises were conducted in Lake Huron waters. Crustacean and rotifer species compositon and abundance generally were characteristic of oligotrophic waters. Crustacean zooplankton cruise mean abundances were more than twice as large as those reported from Lake Huron in 1971, although not as high as reported from southern Lake Huron in 1974. Rotifers occurred in even greater abundances in sourthern Lake Huron in 1974 than over the whole lake in 1980. Differences in abundance across time may reflect changes in the trophic status of the lake or differences in sampling methods and locations. The 1980 zooplankton community was strongly dominated by crustaceans, the probable major grazers on the phytoplankton community. Rotifers, because of their possible greater sensitivity to food limitations and their greater potential rate of population increase, may be the best zooplankton indicators of trophic condition. However, crustacean zooplankton may be better indicators of ecosystem structure (because of their vulnerability to fish predators) and function (because of their major role in grazing).