Objective: To identify the brain regions involved in the voluntary control of pelvic floor and of leg muscles, functional magnetic resonance imaging was performed with a 3.0 Tesla scanner. Method: Paced by auditory cues, 17 male right-handed volunteers carried out three tasks: 1) contractions of the pelvic floor (mimicking the interruption of micturition); 2) toe movements (right side); 3) near-isometric contractions of right knee extensor muscles (12 subjects). The pace was either fast (0.7 Hz), with repetitive short contractions, or slow, with continuous contraction-relaxation cycles that lasted 4 seconds each. Brain images were continuously acquired with a BOLD-sensitive echoplanar imaging technique during these tasks. Results: Regardless of the pace, voluntary contractions of the pelvic floor were associated with significant activity of the medial wall that involved mainly the supplementary and cingulate motor areas (SMA, CMA), and with BOLD signals of the left insula, putamen, thalamus, and temporal gyrus. Activity of the SMA was generally stronger during fast than during slow contractions, although the individual patterns of brain activation differed considerably. Surprisingly, we found hardly any activity in the precentral gyrus during pelvic floor contractions of either pace. The cortical representation of the pelvic floor muscles overlapped strongly with regions that were active during toe movements. This pattern was confirmed by fMRI investigations in another group of subjects (n = 17) where leg muscles of both sides were contracted. Conclusion: The main motor representation of the pelvic floor is not located at the margo superior cerebri ("Mantelkante") of the precentral gyrus, as the classic figure of the homunculus might suggest. It is rather situated in the medial wall (mainly the SMA) and overlaps considerably with the representations of foot and calf muscles. Supported by Deutsche Forschungsgemeinschaft (DFG grant KU 1937/2-1)