A descriptive study to determine the causes of low vision and blindness in children attending the Pacelli School for the Blind in Lagos State, Nigeria. A standardised methodology was used with structured and semi-structured questioinaires. Twenty-six children aged below 16 years who were identified as having low vision and blindness were examined to determine the causes of the low vision and blindness. The anatomical sites of diseases leading to low vision and blindness in these children were retina (30.8%), lens (23.1%), glaucoma (19.2%), cornea (11.5%) and optic nerve (7.7%). Aetiologically, 38.5% of low vision was due to hereditary factors, 23.1% intra-uterine, 15.4% others and unknown in 23%. Retinal dystrophy was the most common cause of low vision and blindness, while congenital cataract and glaucoma were the major causes of avoidable blindness. Very few cases of corneal scar (Measles/Vitamin A deficiency) were seen. The causes of low vision appeared to be different from those of blindness as hereditary and intra-uterine factors were mainly responsible for low vision. It is recommended that these children be identified early, through low vision care programmes and those with avoidable causes treated accordingly.