Objectives In childhood (>6 years-old) and adolescence, fitness testing is feasible, reliable and related to later health. The purpose of this study was to examine the feasibility and reliability of a field-based fitness-test battery in preschool children. Design Repeated measures. Methods A total of 161 preschoolers aged 3 to 5 years participated in the study. Anthropometry, cardiorespiratory fitness, muscular strength and motor fitness were tested twice (2 weeks apart) using weight, height, waist circumference, PREFIT 20m shuttle run, handgrip strength, standing long jump, 4×10m shuttle run and one-leg stance tests, respectively. Results The main results indicated that all tests are feasible and highly reliable (mean differences, weight=0.04kg, height=0.22cm, waist circumference=−0.08cm, PREFIT 20m shuttle run=2.00 laps, handgrip strength=−0.24kg and 4×10m shuttle run=0.12s), in preschool children, except for the standing long jump test and one-leg stance test (mean differences of −7.31cm and 8.01s). After some methodological adaptations, reliability for standing long jump was improved in a replication study (i.e. from −7 to −2cm). We observed evidence of heteroscedasticity in the 4×10m shuttle run and one-leg stance tests. Conclusions The PREFIT battery is a feasible and reliable tool to assess physical fitness in preschool children yet standing long jump has shown mixed findings and requires further studies. The one-leg stance test showed poor reliability in our study and if confirmed by future studies, its use in 3 to 5 years-old would not be recommended. Future studies should consider the mean differences provide in this study to explain the changes in test performance.