The purpose of this study was to compare fast dynamic magnetic resonance imaging (MRI) with colpocystodefecography (CCD) in the evaluation of pelvic floor descent in women. Thirty-five women with clinical evidence of pelvic floor descent were studied. A fast single-shot MR sequence was performed in the supine position during pelvic floor relaxation and during maximal pelvic strain. On the same day, a dynamic CCD was performed with the patient seated on a stool-chair. The degree of descent of the bladder, vagina, and anorectal junction was evaluated as the vertical distance between the pubococcygeal line and the bladder base, the vaginal vault, and the anorectal junction, respectively. A bulge of more than 3 cm measured as the distance between the extended line of the anterior border of the anal canal and the tip of the rectocele was interpreted as a rectocele. MRI was compared with CCD during maximal pelvic strain (CCD 1) and during voiding and defecation (CCD II). CCD was considered as the gold standard. Compared with clinical examination, CCD I showed a larger number of involved compartments, except for the middle compartment. CCD II was superior to clinical examination in all cases. In comparison with CCD I and especially CCD II, MRI had a lower sensitivity, especially for the anterior and middle compartment. Even four enteroceles seen on CCD II were not detected by MRI. When CCD I and CCD II were compared, a cystocele, a vaginal vault prolapse, an enterocele, and a rectocele were more readily seen on CCD II than with CCD I. When compared with CCD, supine dynamic MRI is unreliable, especially in the anterior and middle compartment. Even in the detection of enteroceles CCD was superior to MRI. In general, the best results with MRI can be expected for evaluation of the rectum.