Clinical experience suggests a heightened risk associated with the transition to maintenance dialysis but few national studies have systematically examined early mortality trajectories. Here we calculated weekly mortality rates in the first year of treatment for 498,566 adults initiating maintenance dialysis in the United States (2005-2009). Mortality rates were initially unexpectedly low, peaked at 37.0 per 100 person-years in week 6, and declined steadily to 14.8 by week 51. In both early (weeks 7-12) and later (weeks 13-51) time frames, multivariate mortality associations included older age, female, Caucasian, non-Hispanic ethnicity, end-stage renal disease (ESRD) from hypertension and acute tubular necrosis, ischemic heart disease, estimated glomerular filtration rate of 15 ml/min per 1.73 m(2) or more, shorter duration of nephrologist care, and hemodialysis, especially with a catheter. For early mortality risk, adjusted hazard ratios of 2 or more were seen with age over 65 (5.80 vs. under 40 years), hemodialysis with a catheter (2.73 vs. fistula), and age 40-64 (2.33). For later mortality risk, adjusted hazard ratios of 2 or more were seen with age over 65 (4.32 vs. under 40 years), hemodialysis with a catheter (2.10 vs. fistula), and age 40-64 (2.00). Thus, low initial mortality rates question the accuracy of data collected and are consistent with deaths occurring in the early weeks after starting dialysis not being registered with the United States Renal Data System.