Two cases of physiologic sinusoidal FHR pattern and one case of pathologic sinusoidal FHR pattern recorded on fetal actocardiograms are reported. The physiologic sinusoidal FHR patterns were recorded during periodic fetal respiratory movements and sucking movements. The physiologic sinusoidal FHR patterns were accompanied and synchronized with periodic fetal movement bursts. The pathologic sinusoidal FHR pattern observed in a case of severe fetal anemia due to massive fetal-to-maternal hemorrhage was not accompanied by any fetal movement bursts. It is suggested that with the use of fetal actocardiogram physiologic sinusoidal FHR pattern can be distinguished from pathologic sinusoidal FHR pattern.