Abstract Study question Are there any differences in the chance of a live birth using donor or partner semen in the different groups of women attending fertility clinics? Summary answer The chance of a live birth improves using donor semen for Intrauterine Insemination (IUI) treatments. No difference is observed for In Vitro Fertilization (IVF) treatments. What is known already Few studies regarding the efficacy of ART treatments using donor semen are available and most of them focus only on IUI treatments. Moreover, they usually do not take into account the different groups of women utilizing them or possible differences with the use of male partner semen. Study design, size, duration Danish nationwide cohort study based on health registers including all ART treatments from 2007 to 2017. The number of treatments in women using donor semen was 31540 for IUI and 7770 for IVF. For women using partner semen the number of treatments was 80949 for IUI and 74425 for IVF. ART treatments in women using donor semen were further subdivided into three groups based on women's relationship status: different-sex couples single women, and same-sex couples. Participants/materials, setting, methods Live birth chance per ART treatment cycle, IUI or IVF, using donor or partner semen has been assessed. In a subanalysis, the difference in a live birth was also evaluated comparing women using partner semen and women using donor semen stratified according to the partner with whom they attend the fertility clinics. The crude and confounders adjusted odds ratio (OR and aOR) were obtained by multilevel logistic regression. Main results and the role of chance A live birth was obtained in 13.9% of IUI treatments in women using donor semen compared to 12.3% in women using partner semen with an aOR of 1.33 (95% CI: 1.27-1.40). More in detail, for different groups of women using donor semen the aOR of live birth after IUI treatments was: aOR 1.48 (95% CI: 1.38-1.59) in women with male partners using donor semen, aOR 1.20 (95% CI: 1.13-1.28) in single women and aOR 1.46 (95% CI: 1.32-1.62) in women with female partners using donor semen. For what concern IVF treatments, 20.7% of treatments in women using donor semen and 25.7% of treatments in women using partner semen resulted in a live birth. The aOR was 0.99 (95% CI: 0.92-1.06). Moreover, for the different groups of women using donor semen compared to women using partner semen, the aOR of live birth after IVF treatments was: aOR 1.16 (95% CI: 1.02-1.32) in women with male partners using donor semen, aOR 0.88 (95% CI: 0.80-0.96) in single women, and aOR 1.20 (95% CI: 1.00-1.44), in women with female partners using donor semen. Limitations, reasons for caution Being an observational study, it is not possible to exclude the presence of unknown confounders or residual confounding which might affect the results. Wider implications of the findings This is one of the few studies assessing the ART success chances using donor or partner semen with attention to the now diverse population groups receiving ART treatments. We hope our results would be useful to healthcare professionals to better advise and help all women and couples attending fertility clinics Trial registration number not applicable