In the four Nordic countries, Denmark, Finland, Norway and Sweden, data were compiled from altogether 30 in vitro fertilization (IVF) clinics regarding their treatment outcomes. Two small, recently established IVF clinics in Finland did not respond to the postal inquiry used for data collection. For each clinic, data were collected from the time they commenced activities until June 1989. Preliminary data for the latter half of 1989 was also gathered. The first IVF-baby in this data set was born in Gothenburg in 1982. Seven years later, in December 1989, altogether 35 clinics in the four countries were in operation and 1,290 children had been born. The largest number of clinics, 12, was to be found in Sweden but the number of treatment cycles in relation to the population was highest in Norway with about 340 treatments per million inhabitants annually during 1988-89, with Sweden in second place: 190 treatments per million inhabitants. The ratio of private to public clinics was highest in Finland, where four out of ten clinics were privately run. A mean clinical pregnancy rate per embryo transfer of 20% was recorded and 85% were singleton pregnancies. Spontaneous abortions occurred in 25% and the ectopic pregnancy rate was 7% of all clinical pregnancies. The 'take home baby rate' for 1988-89 was 13% per embryo transfer. There were no major differences between the four countries.