Physical inactivity contributes to the frailty and the decline in function that develops over time among patients with end-stage renal disease. We assessed physical activity among 1547 ambulatory patients new to dialysis in the United States Renal Data System Comprehensive Dialysis Study. We used a self-reporting Human Activity Profile that included Maximal and Adjusted Activity Scores and compared results to established norms by age and gender. Physical activity was found to be extremely low with scores for all age and gender categories below the 5th percentile of healthy individuals and 95% of patients had scores consonant with low fitness. Older age, female gender, diabetes, atherosclerotic disease, and a low level of education were associated with lower activity scores assessed by univariate and multivariable linear regression analysis. Higher serum albumin, creatinine, and lower body mass index, but not hemoglobin levels, were associated with greater physical activity. By multivariable analysis, patients on hemodialysis using a catheter reported lower levels of physical activity compared to those on peritoneal dialysis, hemodialysis using an arteriovenous fistula, or with a graft. Lower Maximal and Adjusted Activity Scores were associated with poor physical function and mental health. Hence, physical activity is distressingly low among patients new to dialysis. Thus, strategies to enhance activity in these patients should be explored.