STUDY QUESTION: Is the outcome of donor recruitment influenced by the country in which recruitment took place or the initial identity (ID)-release choice of applicants? SUMMARY ANSWER: More applicants are accepted as donors in Denmark than in the USA and those who choose ID release are more frequently accepted than those who do not. WHAT IS KNOWN ALREADY: The successful recruitment of sperm donors is essential to provide a range of medically assisted reproduction (MAR) procedures, which rely upon donor sperm. However, while much has been written about the medical screening and assessment of sperm donors from a safety perspective, relatively little has been written about the process of recruiting donors and how it works in practice. There are differences in demographic characteristics between donors who choose to allow their identity to be released to their donor offspring (ID release) compared to those who do not (non-ID release). These characteristics may also influence the likelihood of them being recruited. STUDY DESIGN, SIZE, DURATION: A total of 11 712 men applied to be sperm donors at a sperm bank in Denmark and the USA during 2018 and 2019. PARTICIPANTS/MATERIALS, SETTING, METHODS: Anonymized records of all donor applicants were examined to assess the number passing through (or lost) at each stage of the recruitment process. Statistical analysis was carried out to examine differences between location (Denmark or USA) and/or donor type (ID release versus non-ID release). MAIN RESULTS AND THE ROLE OF CHANCE: Few applicants (3.79%) were accepted as donors and had samples frozen and released for use; this was higher in Denmark (6.53%) than in the USA (1.03%) (χ2 = 243.2; 1 degree of freedom (df); z = 15.60; P < 0.0001) and was higher in donors who opted at the outset to be ID release (4.70%) compared to those who did not (3.15%) (χ2 = 18.51; 1 df; z = 4.303; P < 0.0001). Most candidate donors were lost during recruitment because they: withdrew, failed to respond, did not attend an appointment, or did not return a questionnaire (54.91%); reported a disqualifying health issue or failed a screening test (17.41%); did not meet the eligibility criteria at the outset (11.71%); or did not have >5 × 106 motile sperm/ml in their post-thaw samples (11.20%). At each stage, there were statistically significant differences between countries and the donor's initial ID choice. During recruitment, some donors decided to change ID type. There were no country differences in the frequency in which this occurred (χ2 = 0.2852; 1 df; z = 0.5340; P = 0.5933), but it was more common for donors to change from non-ID release to ID release (27.19%) than the other way around (11.45%) (χ2 = 17.75; 1 df; z = 4.213; P < 0.0001), although movements in both directions did occur in both countries. LIMITATIONS, REASONS FOR CAUTION: No information was available about the demographic characteristics of the applicants, which may also have influenced their chances of being accepted as a donor (e.g. ethnicity and age). Donor recruitment procedures may differ in other locations according to local laws or guidelines. WIDER IMPLICATIONS OF THE FINDINGS: A better understanding of when and why candidate donors are lost in the recruitment process may help develop leaner and more efficient pathways for interested donors and sperm banks. This could ultimately increase the number of donors recruited (through enhanced information, support, and reassurance during the recruitment process) or it may reduce the financial cost to the recipients of donor sperm, thus making it more affordable to those who are ineligible for state-funded treatment. STUDY FUNDING/COMPETING INTEREST(S): The study received no funding from external sources. All authors are Cryos employees or members of the Cryos External Scientific Advisory Committee.N/A.