Safety concerns have been raised about nighttime and weekend patient care, but it is unknown whether these issues affect liver transplantation. We sought to identify the impact of nighttime and weekend liver transplants on graft and patient survival. We used the United Network for Organ Sharing database to review adult liver transplants from 1987 to 2010. Comparisons were made between nighttime and daytime operations and between weekday and weekend operations. Cox proportional hazard ratios (HRs) were determined 30, 90, and 365 days after transplantation after we controlled for relevant factors; 94,768 transplants were included in the analysis. The patient survival rates at 30, 90, and 365 days for nighttime operations were 96%, 93%, and 86%, respectively. The patient survival rates at 30, 90, and 365 days for weekend operations were 95%, 92%, and 86%, respectively. These rates did not significantly differ from those for daytime and weekday operations, respectively. The graft failure rate was unchanged at 30 and 90 days for weekend transplants but was modestly increased at 365 days [HR = 1.05 (95% confidence interval = 1.01-1.11)]. Graft survival was unaffected by nighttime transplantation. Nighttime and weekend operations for liver transplantation do not affect patient or graft survival, and this testifies to the patient safety measures in place. Liver Transpl, 2012. © 2012 AASLD.