*Purpose: Our kidney transplant (KTx) program serves a medically underserved and racially diverse area of a southern state. The purpose of this study was to evaluate the effect of HLA mismatch (mm) on death-censored graft failure.

*Methods: Adult (age ≥ 18 years) recipients of kidney-only transplants of deceased donors from 1995-2018 were eligible for inclusion. A multivariable Cox cause-specific hazard model was used to evaluate the effect of HLA mismatching on risk of death-censored graft failure adjusting for donor and recipient characteristics. Hazard ratio (HR) and 95% confidence interval (CI) are presented as measures of strength of association and precision, respectively.

*Results: Consecutive 921 KTx recipients (75% African American (AA), 22% white, and 3% other; 44% female and 56% male) were included in the analysis. The median follow-up was 72 months. AA recipients were younger, had higher BMI, more DGF, and higher HLA-A, B, DR, and DQ mm than non-AA recipients. There was no statistical difference in donor characteristics between AA and non-AA recipients. Multivariable Cox hazard analysis indicated significant increased risk of death-censored graft failure in patients with 1 or 2 DQ mm (HR=2.19; 95% CI=1.40,3.41 and HR=1.96; 95% CI=1.14,3.37, respectively). (Table). Effect modification suggests the effect of DQ mm may be more pronounced in AA recipients. Among AA recipients, the HR for 1 DQ mm versus 0 DQ mm was 2.79 (95% CI=1.67, 4.65) and for 2 DQ mm, 2.52 (95% CI=1.38, 4.59). Among non-AA recipients, the HRs were not statistically significant. Mismatch at the A, B, or DR loci had minimal impact on risk of death-censored graft failure.

*Conclusions: HLA-DQ plays an important role in graft survival, especially in AA recipients. Additional studies using national data is warranted.

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