Low vision is a major cause of morbidity and has profound effects on the quality of life for many people as it inhibits/reduces mobility and economical well being of the affected individuals and their families. The objective of the study was to determine the magnitude and causes of low vision among primary school children in Kibaha district in Tanzania. Primary schoolchildren were recruited for the study. The inclusion criterion was individual child with low vision of less than 6/18. Visual examination was used for screening the children to identify those with vision less than 6/18. Snellen's chart was used to measure visual acuity of the children with low vision. A total of 400 (6-17 years) schoolchildren were screened. Thirty-eight (9.5%) had low vision. The prevalence of low vision was statistically higher (N=33; 87%) among 12-17years old than among 6-11 years old (13%) (P<0.05). Of the 38 children with low vision, the prevalence in females (68%) was statistically higher than in males (32%). There were multiples causes of low vision among affected children. Congenital anomalies accounted for the largest proportion (65%) of the causes of low vision. In twenty-three (60%) of the children (12-17 years), low vision was due to retinopathies. Fifty-five percent of the children with refractive error were aged between 6-11 years. Among the cases, 8 (54%) had low vision caused by uncorrected refractive errors while the rest (46%) were due to other types of refractive errors. Two children had corneal scars; one with central and another with whole corneal scar. In conclusion, prevalence of low vision among schoolchildren in Kibaha district is high and increases with age. The main causes are congenital anomalies. There is need for an early detection of the possible causes and appropriate treatment to reduce the condition among schoolchildren. It is therefore important that the district Council Health Management Team establishes school eye screening programme for early detection and treatment. It is equally important to strengthen advocacy programme targeting schoolchildren, teachers and caregivers on the public health importance of low vision.