The purpose of this study was to determine the reliability of short-term power output, heart rate (HR) response during and after a treadmill test, and time to complete a 25-m dash in healthy preschool children. Thirty-two 3- to 5-year-old boys and girls completed two sessions approximately one week apart. Intraclass correlation coefficient (ICC) and coefficient of variation (CV) were calculated to evaluate reliability. Power output was found to be reliable with ICCs ranging from 0.83 to 0.93 and CVs from 8.1 to 9.7%. Time to complete the 25-m dash was highly reliable (ICC = 0.91, CV = 3.7%). Reliability for HR at submaximal exercise (ICC = 0.28, CV = 18.8%) and HR recovery (ICC = 0.42, CV = 14.0%) was not as strong. These findings should assist in determining appropriate fitness tests for preschoolers.