Reported in this paper is a mesonephroid carcinoma in the vagina of a primigravida, 27 years of age, in the 27th or 28th week of pregnancy. The carcionoma originated from Gartner's duct and is characterised by typical papillary structures. Such carcionoma quite often cannot be morphologically differentiated from metamesonephroid carcionomas which originate from Mueller's epithelium to occur on the same site. Both tumour forms are rather often be considered an entity in relevant literature. The development of that carcinoma during gravidity is considered accidental. - Included in the therapeutic approach were Caesarean section, radical hysterectomy, including radical adnexectomy and removal of a 5-cm vaginal collar, removal of the Douglas peritoneum because of visible intraperitoneal metastasation, and extensive lymphonodectomy, all in one session. - Biaxial telecobalt pendulum irradiation followed postsurgically, the focal dose being 7,000 rd. No sign of recurrence has been recordable from follow-up checks and clinical examinations, one year from surgery.