This paper discusses the need for event-condition-action (ECA) rules in spatio-temporal databases and outlines a generic scenario for them. A proposal for the implementation of ECA rules is then presented in which several implementation alternatives for different spatio-temporal rule types are considered. Through a series of experiments, these implementation alternatives are evaluated to determine which are most appropriate in each case. The article closes with a discussion of practical uses of these alternatives in earlier studies and a section of concluding remarks.