Visual acuity testing using Teller Acuity Cards was carried out on 78 infants and children affected by cerebral palsy (CP). Age of testing was between 3 and 109 months. The aim of the study was to investigate the usefulness of acuity cards in patients with CP, and to relate visual outcome with the type of CP, MRI findings, mental levels and motor disabilities. Visual acuity estimates were obtained for 60 children: acuity values were within normal values for age for 17 and below the 5th percentile for 43. Cerebral blindness was diagnosed in 10 patients. Eight infants were not testable, mainly because of behavioural problems. The overall success rate was 88%. Visual impairment in most infants with low acuity and in all blind children was not due to ophthalmological abnormalities. Visual outcome was significantly related to the type of CP, with hemiplegic children showing the best results and tetraplegics the worst. Cerebral blindness was significantly correlated with tetraplegia, the severity of lesions in the optic radiations, and visual cortex areas, as indicated by MRI, and the degree of mental, motor and oculomotor deficit. These correlations were mainly due to the blind subjects, who consistently showed major MRI abnormalities and severe motor, mental and oculomotor impairment. Longitudinal results obtained for 45 children showed visual outcome stable over time in 64.4% of cases, improvement in 6.6% and deterioration in 28.9%.