OBJECTIVE: Cardiothoracic (CT) surgery remains a male-dominated specialty. Letters of recommendation (LORs) influence trainee selection and are vulnerable to biases. We aimed to qualitatively assess differences in LORs to integrated residency on the basis of applicant gender. METHODS: LORs for applicants who interviewed at a single integrated CT residency program during one cycle were selected and pooled by applicant gender. Gendered and identifying references were redacted. Letters were analyzed by a thematic analysis approach and managed through NVivo software. RESULTS: Thirty LORs across 8 male applicants and 43 LORs across 11 female applicants were analyzed. There was no noticeable difference between the frequency of positive attributes assigned to each gender. Research accomplishments was the most emphasized competency, with no gender-based difference identified. LORs for female applicants tended to be longer and include stronger positive adjectives. For male applicants, descriptions of external recognition were almost exclusively via mention of scholarships or research, whereas female applicants were more likely to receive word-of-mouth recognition. Letter writers often attested to male applicants' commitment to CT surgery, whereas female applicants received more commentary around effective patient care. CONCLUSIONS: Letters for men tended to focus on research accolades and career commitment, whereas letters for women were longer and more likely to emphasize patient care or faculty endorsement. Future studies may discern whether this phenomenon reflects stronger applicant-writer relationships for female applicants or a disadvantageous approach by letter writers for female applicants that relies on subjective rationale.