BACKGROUND: Appropriate patient selection for simultaneous heart-kidney transplantation (sHK) in patients with moderate renal dysfunction remains challenging. METHODS: From the United Network for Organ Sharing database (2003-2020), we identified 5678 adults with an estimated pre-transplant glomerular filtration rate (eGFR) between 30 and 45 mL/min/1.73 m2 and no pre-transplant dialysis. Patients undergoing sHK (n = 293) were compared with those undergoing heart transplantation alone (n = 5385) using 1:3 propensity score matching. RESULTS: The sHK utilization rate increased from 1.8% in 2003 to 12.2% in 2020 (p < .001). After matching, 1 and 5-year survival was 87.7% (95% confidence interval [CI] 83.3-91.0) and 80.0% (95% CI 74.2-84.6) after sHK, and 87.3% (95% CI 85.2-89.1) and 71.8% (95% CI 68.4-74.9) after heart transplant alone (p = .04). In the subgroup analysis, sHK was associated with a 5-year survival benefit only in patients with 30 < eGFR ≤ 35 mL/min/1.73 m2 (p = .05) but not in those with 35 < eGFR < 45 mL/min/1.73 m2 (p = .45). Patients who underwent heart transplants alone also had a higher incidence of becoming chronic dialysis-dependent after transplant within 5-year follow-up (10.2%, 95% CI 8.0-12.6 vs. 3.8%, 95% CI 1.7-7.1, p = .004). The 5-year incidence of subsequent kidney waitlisting and transplants after heart transplants alone was 5.6% and 1.9%, respectively. CONCLUSION: Among propensity-matched patients without pre-transplant dialysis, compared to heart transplants alone, sHK had improved 5-year survival in those with 30 < eGFR ≤ 35 but not in those with 35 < eGFR < 45 mL/min/1.73 m2 . One-year survival was similar irrespective of eGFR. Receiving a kidney after a heart transplant alone is rare under the current allocation system.