Intrauterine devices have been used for over 2000 years. The modern devices (loop, coil and bow) were developed in 1959. The data on 11,222 first insertions from 43 contributing institutions were analyzed by the National Committee on Maternal Health. With the intrauterine loop, expulsions occurred in less than 10% of patients, removals for medical and personal reasons in a further 15%, and pelvic infections in 1.7% during the first year following insertion. Pregnancies occurred during the first year in 2.4% of patients fitted with a loop. Typical of the modern intrauterine devices, the loop is highly effective, readily accepted, and well tolerated by approximately 75% of patients.