Abstract. After observing 2 cases of isolated torsion of the Fallopian tube, we inquired of all surgical and gynaecological departments on the Danish islands of Zealand and Lolland–Falster whether any such cases had been treated during the period 1957–1967. In this way we traced another 8 cases. As the departments concerned serve an area of Denmark with a population of about 3 millions, about half of whom are women, the annual incidence of isolated torsion of the Fallopian tube may be estimated as one in 1,500,000 women. The 10 case histories are briefly reported. Some theories on the aetiology of tubal torsion are mentioned, and the symptoms as well as treatment are discussed.