Background <p>This study aimed to investigate the association between mandatory post-call rest regulation in Türkiye and residency preferences in cardiovascular surgery.</p> Methods <p>This retrospective study was conducted using publicly available data from the official websites of governmental institutions in Türkiye. The primary reference was the ‘’Regulation on Specialty Training in Medicine and Dentistry’’, published in the Official Gazette on September 3, 2022 (Issue No. 31942). The five residency placement periods before and after the enactment of the regulation were categorized as “pre-regulation” and “post-regulation” groups, respectively. Institutions were subgrouped as Ministry of Health hospitals and university medical faculties, while cities were categorized as Istanbul–Ankara–Izmir and other cities. Istanbul–Ankara–Izmir were additionally analyzed as major metropolitan centers with distinct sociodemographic characteristics and advanced healthcare infrastructures. The total number of cardiovascular surgery residency slots and the number of unfilled slots were obtained from the Assessment, Selection and Placement Center (OSYM) reports.</p> Results <p>The mean unfilled slot rate for total cardiovascular surgery residency positions was 36.16 ± 6.88% in the pre-regulation group and 12.43 ± 10.08% in the post-regulation group (<i>p</i> = 0.002). For Istanbul–Ankara–Izmir was 13.33 ± 8.6% in the pre-regulation period and 5.84 ± 5.06% in the post-regulation period (<i>p</i> = 0.132). For other cities, the rates were 57.1 ± 11.19% and 20.91 ± 18.25%, respectively (<i>p</i> = 0.005). In university medical faculties, the rates were 45.55 ± 9.3% before and 20.41 ± 18.45% after the regulation (<i>p</i> = 0.026). In Ministry of Health hospitals, the respective rates were 22.9 ± 10.05% and 6.43 ± 5.88% (<i>p</i> = 0.013).</p> Conclusions <p>The post-regulation period was associated with a lower rate of unfilled cardiovascular surgery residency positions compared with the pre-regulation period.</p>