The classic form of adenomyosis of the tube is characterized by the presence in a firm and thickened segment of medial tubal isthmus of multiple, small, tubular diverticuli of the endosalpinx which pursue a serpiginous course through the tubal wall. The disease is bilateral for about 85 per cent of the cases studied herein.The diffuse form of adenomyosis tubae, probably the more common type, is not identified as often as is the localized form, which is characterized by a nodose isthmus. This is true at operation because of the tendency of most surgeons to consider most types of tubal disease to be postinflammatory states (which this condition closely resembles). It is also true at gross pathologic examination because the customory method of such examination consists of axial opening of the organ by seissors. This maneuver leaves the disease difficult to discern. In situ, the presence of a resilient, firm segment of isthmus, with or without enlargement of that portion (where the ampulla is within normal limits) usually suffices to identify the disease. At pathologic examination, cross sectional study after fixation is the method best suited for identification of the less obvious type.Evidence is submitted which suggests that the disease may not be a result of inflammation. Not the least of this evidence is the rather high incidence of other tubal anomalies among specimens of adenomyosis tubae.For 65 to 75 per cent of 81 cases, a mucosal stroma resembling endometrium rather than endosalpinx has been encountered focally beneath the tubal type of tubule lining. This stroma will be described separately.For 39 married women who had the disease on both oviducts, the incidence of sterility was found to be 64 per cent (±8 per cent∗∗Standard error.). The mechanism of this feature of the disease is not well understood; several possible mechanisms have been suggested.Adenomyosis tubae does not cause dysmenorrhea, although adenomyosis of the uterus is widely held to do so. The frequency of association of adenomyosis tubae and adenomyosis uteri has not been determined.The tendency of the tubules of adenomyosis tubae is to penetrate the myosalpinx and overlying serosa with formation of multiple tuboperitoneal fistulas. These channels, although small, may provide vicarious passage for sperm, ova, blood, bacteria, opaque media used for diagnosis, or endometrial particles between the tubal lumen and the peritoneal cavity.Adenomyosis tubae was discovered among 13 per cent (±3.4 per cent∗) of specimens of tubal pregnancy, and among 7.6 per cent (±2.4 per cent∗) of a control series. Where these two conditions are associated in one specimen the adenomyotic process often involves the tube at precisely the medial angle of the pregnancy sac.Adenomyosis of the tube is suggested clinically by a long period of sterility without apparent cause, and by isthmic obstruction as seen by salpingogram.The aim of this presentation is the stimulation of widespread recognition of the disease so that problems concerning the patency of tubes in which it is present, as well as many other problems, may be decided. It is probably present among 5 to 10 per cent of the general female population. Further information concerning it awaits large-scale recognition, with clinical, pathologic and physiologic study of its relation to serosal endometriosis, endometrium-like endosalpinx, sterility and many other problems.It is likely that little will be accomplished surgically for the condition until there is improvement in the technique of tubal resection and reimplantation.It is felt that the disease may be more significant than is generally recognized.A discussion of its surgical disposition is included.