BACKGROUND: Unilateral visual impairment (UVI) as a result of amblyopia or refractive error is common in childhood, but its functional significance remains largely unexplored. AIM: To investigate the influence of visual acuity and stereoacuity on the performance of preschool children on tasks requiring visuomotor skills and visuospatial ability. METHODS: Children with normal (6/6) visual acuity (VA) in both eyes and children with UVI ranging from 6/9 to 6/60, with no strabismus and normal vision in the fellow eye, were assessed on a neurodevelopmental test battery of visually guided tasks. RESULTS: 50 children (mean age (SD): 52.4 (5.7) months; median (range) VA: 6/9 (6/6 to 6/60); median (range) stereoacuity: 70 seconds arc (40-absent)) completed the test battery. UVI and stereoacuity correlated moderately (Pearson's r = 0.537, p < 0.001) but seven of 28 children with impaired VA had normal stereoacuity (< 70 seconds arc) while five of 22 with normal VA had abnormal stereoacuity. Stereoacuity correlated with performance on a task requiring fine hand-eye coordination and a task measuring visuomotor integration. UVI did not correlate with performance on any test battery items. CONCLUSIONS: UVI itself does not appear to relate to visuomotor actions, except when associated with reduced stereoacuity. Stereoacuity appears to have an influential role in fine visuomotor actions and spatial representation in preschool children.