Objective: To evaluate the modified Teller visual acuity test as a mass screening tool for testing visual acuity in infants and preverbal children. Design: Prospective case series. Participants: A total of 1126 healthy children undergoing mandatory examination at the Mother and Child Health Center. Intervention: Visual acuity was tested by the modified Teller visual acuity test. Main Outcome Measures: Visual acuity was measured in all children. Clinical evaluation was performed in children who failed the Teller acuity test and in a control group. Results: Visual acuity was below the normal range in 5% of the children. In the study group referred for complete eye examination, there were 9% false-negative and 44% false-positive results. In the age range of 12 to 17 months, false-negative and false-positive results were obtained in 5.6% and 50% of the children, respectively. Conclusions: The Teller acuity card procedure can be used for vision screening in preverbal children. Testing was associated with a high rate of false-positive results.