STUDY QUESTIONWhat are oocyte donors and sperm donors' attitudes towards disclosure and relationship to donor offspring?SUMMARY ANSWEROocyte and sperm donors in an identity-release donor programme support disclosure to donor offspring and have overall positive or neutral attitudes towards future contact with offspring.WHAT IS KNOWN ALREADYThere is a global trend towards open-identity gamete donation with an increasing number of countries introducing legislation allowing only identifiable donors. While women and men who enrol in identity-release donor programmes accept that they may be contacted by donor offspring, there is limited knowledge of their attitudes towards disclosure to donor offspring and how they perceive their relationship to potential donor offspring.STUDY DESIGN, SIZE AND DURATIONThe present study is part of the ‘Swedish study on gamete donation’, a prospective cohort study including donors at all fertility clinics performing donation treatment in Sweden. During a 3-year period (2005–2008), donors were recruited consecutively and a total of 157 oocyte donors and 113 sperm donors (who did not donate to a specific ‘known’ couple) were included prior to donation. Participants in the present study include 125 female (80%) and 80 male donors (71%) that completed two follow-up assessments.PARTICIPANTS/MATERIALS, SETTINGS AND METHODSParticipants completed two postal questionnaires 2 months after donation and 14 months after donation. Attitudes towards disclosure to donor offspring were assessed with an established instrument. Perceptions of involvement with donor offspring and need for counselling was assessed with study-specific instruments. Statistical analyses were performed with non-parametric tests.MAIN RESULTS AND THE ROLE OF CHANCEA majority of oocyte and sperm donors supported disclosure to donor offspring (71–91%) and had positive or neutral attitudes towards future contact with offspring (80–87%). Sperm donors reported a higher level of involvement with potential donor offspring compared with oocyte donors (P = 0.005). Few donors reported a need for more counselling regarding the consequences of their donation.LIMITATIONS, REASONS FOR CAUTIONWhile the multicentre study design strengthens external validity, attrition induced a risk of selection bias. In addition, the use of study-specific instruments that have not been psychometrically tested is a limitation.WIDER IMPLICATIONS OF THE FINDINGSThe positive attitudes towards disclosure to offspring of female and male identity-release donors are in line with previous reports of anonymous and known donors. While our results on donors' general positive or neutral attitudes towards future contact with potential donor offspring are reassuring, a subset of donors with negative attitudes towards such contact warrants concern and suggests a need for counselling on long-term consequences of donating gametes.STUDY FUNDINGThe ‘Swedish study on gamete donation’ was funded by the Swedish Research Council, the Swedish Council for Health, Working Life and Welfare...