Activity in the human primary motor cortex, the premotor cortex and the supplementary motor area during a delayed cued finger movement task was measured by time-resolved functional magnetic resonance imaging. Activity during movement preparation can be resolved from activity during movement execution in a single trial. All three areas were active during both movement preparation and movement execution. Activity in the primary motor cortex was considerably weaker during movement preparation than during movement execution; in the premotor cortex and the supplementary motor area, activity was of similar intensity during both periods. These observations are consistent with results from single neuronal recording studies in primates.