Intracytoplasmic sperm injection (ICSI) has been studied in this animal research programme since 1990. In 1993, the technique was first applied clinically and up to the present time (September 1994), a total of 456 couples have been studied in 538 cycles. The principal indication for the use of ICSI has been severe male sub-fertility as judged by a semen analysis. In addition, men with high titres of antisperm antibodies, blockage of the vas deferens and neurological disorders such as spinal cord lesions have been included in the programme. Men with genetic disorders such as cystic fibrosis and acrosome-deficient spermatozoa have also been treated successfully. The overall fertilization rate using ICSI was 59%, which is similar to the conventional in vitro fertilization (IVF) programme in Göteborg, however, the pregnancy rate per embryo transfer (29%) and the ongoing pregnancy rate per transfer (22%) were slightly lower. The total number of pregnancies was 144 with 111 of the pregnancies either ongoing or already delivered. To date, 36 healthy children have been born following 29 deliveries and no major malformations have been diagnosed. Being the first programme in Scandinavia to perform ICSI, this unit has experienced long waiting lists which indicates that severe male sub-fertility will be one of the major groups for treatment with assisted reproductive technologies in the future.