Physicians routinely recommend hand squeezing exercises for end-stage renal disease patients with newly placed arteriovenous fistulae (AVF) to increase the rate of fistula maturation. However, this practice has never been shown to actually work. To determine whether hand squeezing has an acute effect on fistula diameter, we examined 23 patients with newly created AVF (1 week to 10 months before study, mean 2.8 months). Using duplex ultrasound, we measured the diameter of the fistula three times before and three times after 5 min of squeezing a rubber ball. Fistula diameter increased in 20 of 23 patients; the mean change in fistula diameter was 9.3% (p < .0001). These data suggest that fistulae do dilate acutely after hand squeezing exercise and that this exercise should continue to be recommended.