The introduction of radiopaque solution into the uterus, fallopian tubes, and peritoneal cavity is performed with respect and some reserve by the gynecologist. The reasons are obvious and well documented. The careful exclusion of contraindications, to be elaborated upon in some detail, the disadvantages of certain radiopaque materials, and the various complications, sometimes fatal, are given due consideration. The ascertainment of anatomical features and technic of introduction are complementary to the observation and interpretation of the radiologist at the fluoroscopic table. The value of the procedure, especially in the treatment of sterility, is reiterated in this paper. The rather extensive literature on the subject shows a majority of authors most enthusiastic. The history of the procedure, the methods, and introduction of different media are worthy of some review. Cary (1), in 1914, reported the use of Collargol, described later in the same year in the German literature by Rubin. Because of irritating reactions, it was discontinued. The next report was in 1923 by Kennedy (2), who used 20 per cent sodium bromide. While this author was enthusiastic, others found rather marked reactions (3). In 1922, Lipiodol was used in the spine and joints with favorable results (4). Heuser (5), in 1925, described its use in South America, advising hysterograms in the diagnosis of pregnancy. In 1926 Béclère (6) and others published accounts of the use of Lipiodol for hysterosalpingograms, and since that time many reports have appeared in the French literature. In fact, this substance has extraordinary popularity in France. In 1927 and later, Jarcho (7,8) in America wrote favorably of hysterosalpingography in various uterine, tubal, and ovarian diseases. Many other papers have subsequently appeared. Iodochlorol was described as another popular oily medium (9). In 1938, Titus, Tafel, McClellan, and Messer (10) tried Skiodan with acacia, with good results, rapid absorption, and less reaction. This was to meet the growing anxiety over reactions to the oily media. In 1941, Rubin (11) introduced Viscorayopaque, a complex iodine compound in polyvinyl alcohol. This rapidly absorbed, water-soluble material has been a great improvement. Palmer (12) recommended Lipiodol-F, a less viscid oil solution, as having produced no serious reactions in his experience of 196 cases. A consideration of these various media, on the one hand oily and on the other watersoluble, is of great importance in view of reactions that may be produced. The oily materials, such as Lipiodol, are very slowly absorbed, sometimes over weeks, months, or even years. The very viscid oil is readily trapped in occluded or sacculated tubes and commonly produces a foreign-body reaction with partial absorption of oil into phagocytes. The microscopic picture of this type of inflammation is very characteristic.