The causes of acute retention of urine in the female have been enumerated and classified. They may be found in any of the standard textbooks on urology. It is, however, a recognized fact that this condition is not a common one. After a diligent search through the literature I have been unable to find a single case reported which was a result of hematocolpometra. It is not my purpose in this article, therefore, to discuss acute urinary retention in the female in general; but the rarity of its occurrence due to hematocolpometra merits its mention. As the condition suggests, the acute retention was mechanically accomplished. It may therefore be classified as one of the extrinsic causes of urinary retention. A careful history brings out the stages of its gradual development up to the point of emergency. The following history is given to enable the reader to get a composite picture