The current state of the art in automated measurement of grazing rates of zooplankton and bivalves is evaluated. Limitations to the development of automated methods are discussed with reference to theoretical considerations. Different approaches to time-series measurements are examined, and some inadequately investigated time scales for measurement of grazing rates are outlined. Levels of automation of existing experimental systems are described, and a recently developed grazing system based on in vivo fluorescence advanced. The new system is suited to use with zooplankton or bivalves, but depends on precise calibration of in vivo fluorescence. It facilitates rapid measurement of functional response to food concentration, estimation of time-series rates at constant food concentrations, and measurement of rates while simulating patchy food distribution. Results derived from experiments with krill (Nyctiphanes australis) and cockles (Chione stutchburyi) using this grazing system are presented, and some future directions for instrument development suggested.