BACKGROUND: The objective was to assess crude 5-year delivery rates after assisted reproductive technology (ART) treatment, intrauterine inseminations (IUI), spontaneous conceptions (SC) and adoptions in a large infertile cohort. METHODS: A prospective longitudinal survey comprised 1338 infertile couples starting public infertility programmes offering IUIs and three free ART cycles during 2000-2001. The cohort was cross-linked with the National Medical Birth Register to obtain delivery rates for all 1338 couples. More detailed data were available from 817 women responding to a 5-year follow-up questionnaire (response rate 74.7%). Fifty-seven percent (466/817) of the couples had received treatment prior to inclusion in the study with an average of 4.1+/-2.8 infertility treatments before referral. RESULTS: Of the 1338 couples, 69.4% had at least one delivery within 5-years of follow-up. For women <35 years 74.9% had delivered compared with 52.2% of those aged > or =35 years. The mean number of children was 1.6, and 52.1% had more than one child. Of the 817 women who provided questionnaire data, 18.2% (149/817) delivered after SC, two-thirds of these after a previous ART delivery. Adoption of a child occurred for 5.9% (48/817) of the women. Positive prognostic factors for delivery were male infertility, female age <35 years, <3 years of infertility and less than three previous treatment cycles. CONCLUSIONS: A crude delivery rate of 69.4% in the total population 5 years after referral to tertiary hospital centres with 6.6% deliveries after SC in the subpopulation responding to the questionnaire indicates a high efficacy of modern infertility treatments.