Diverticulosis of the Fallopian tubes is uncommon, but is nine times as common in Negro women of Jamaican origin as in Caucasian women living in Bristol. 58 examples were encountered in 918 hysterosalpingograms done in Kingston, Jamaica (426) and in Bristol (492) from 1968 to 1972. In 41 cases (72%) diverticulosis was bilateral. There are several possible predisposing clauses, of which infection, including tuberculosis, is the most important. The radiological appearances are distinctive, but, with the possible exception of tuberculosis, do not give any indication of the cause. Infertility was the commonest clinical association of diverticulosis. Among infertile patients, hydrosalpinx and tubal obstruction were slightly commoner in the presence of diverticulosis, and the significance of this is discussed. Ectopic pregnancy is the most important associated condition and diverticulosis predisposes to its occurrence. Hysterosalpingography is indicated following ectopic pregnancy to show whether there is diverticulosis of the contralateral tube, as this may influence prognosis and management.