Background: Accumulation of 18F-fluorodeoxyglucose (18F-FDG) in the uterine endometrium and uterine motility are dependent on menstrual cycle. However, the relationship between them remains unknown. Purpose: To investigate the relationship between radiometabolic activity of 18F-FDG in the uterus and uterine motility observed by cine magnetic resonance imaging (MRI). Material and Methods: The study population consisted of 65 healthy, fertile women, selected from 229 women who underwent positron emission tomography (PET), computed tomography (CT), and MRI for cancer screening at our facility. They were divided into three groups according to their menstrual cycle phases: menstrual, follicular-periovulatory, and luteal. Regions of interest (ROIs) were placed over the endometrium and myometrium to calculate the standardized uptake value (SUV). Uterine peristalsis and contraction shown by cine MR imaging were evaluated visually, and the correlation between FDG uptake and uterine movements was assessed. Results: After excluding nine patients due to inadequate images, 56 patients (19 follicular-periovulatory, 27 luteal, and 10 menstrual) were analyzed. FDG uptake of the endometrium, frequency of peristalsis, and the presence of sustained contraction varied according to the menstruation cycle, with a tendency toward greater uptake in the menstrual phase, but there was little relationship between the frequency of uterine peristalsis and FDG accumulation in the uterus. Significantly higher FDG accumulation in the endometrium was observed in patients with sustained contractions (3.321.47) than in those without contractions (2.450.66). Conclusion: Our preliminary data suggest that FDG accumulation in the endometrium tends to be higher in patients with uterine contraction, although there was no significant correlation between uterine peristalsis and FDG uptake in the uterine myometrium or endometrium.