The purposes of this study were to describe the performance of 40 children aged 4 and 5 years on the Pediatric Clinical Test of Sensory Interaction for Balance (P-CTSIB) and to determine whether age- and gender-related differences were present. The P-CTSIB measures standing balance when sensory input is systematically altered. Kruskal-Wallis one-way analyses of variance by ranks (p ≤ .05) were used for comparisons by age and gender. When the 4-year-olds were compared with the 5-year-olds, significant duration differences were found in 4 of the 6 conditions in the heel-toe position of the P-CTSIB. The age-related differences on the remaining 2 heel-toe conditions, as well as on Condition 6 of the feet-together position, approached significance. Gender differences with 4-year-olds and 5-year-olds combined were statistically non-significant in all instances; however, girls performed better on 9 of the 12 conditions of the P-CTSIB. The results indicate that the feet-together position can discriminate between children without balance deficits and children with balance deficits. The heel-toe position is difficult for children aged 4 and 5 years without balance deficits and consequently has limited diagnostic value for this age group.