A study of conducted in the Outpatients' Gynaecological Department of St Elisabeth's of Groote Gasthuis, Haarlem, The Netherlands, to compare the performance of 14 IUCDs, namely the Multiload (ML) Cu 250-standard, the ML Cu 250-short (which has a shortened vertical stem), the ML Cu 250-mini and the ML Cu 375 (which has an increased copper area of 375 mm2). Sound length was the sole method governing insertion: greater than or equal to 7 cm with the ML Cu 250-standard and ML Cu 375, 5-7 cm with the ML Cu 250-short and less than 5 cm with the ML Cu 250-mini. All the ML Cu 250-minis and 10% of the ML Cu 250-shorts were inserted in nulliparous women. Data were recorded and evaluated over a period of 36 months according to the table method Tietze. Performance of the ML Cu 250-standard and the ML Cu 250-short were nearly similar after 3 years of use with a continuation rate of 70,6 and 70,3 and a cumulative pregnancy rate of 1,3 and 1,7 respectively. Results with the ML Cu 250-mini were less successful. The continuation rate after 3 years of use was 60,1 with a cumulative pregnancy rate of 3,1. The expulsion and removal rates because of medical reasons were twice those with the standard model. At 12 months the ML Cu 375 proved to be superior in the prevention of pregnancy compared with the ML Cu 250-standard.