Background: Vitamin A plays vital role in the physiology of vision and immunity. Globally quarters of a billion children are Vitamin A deficient. Vitamin A supplementation of children and mothers during postpartum period is a key strategy to avert the deficiency. However the effect of Vitamin A supplementation on incidence of childhood illnesses is controversial. Objective: To assess the effect of Vitamin A supplementation on the reduction of common childhood illnesses, and to measure the coverage of vitamin A supplementation among children aged 6-59 months and mothers during postpartum period. Methods: A retrospective cohort study which involves comparison between Vitamin A supplemented and nonsupplemented children was conducted in Feb 2008 in Boloso Sore Woreda, Wolayta Zone, SNNPR. A total of 1601 children aged 6-59 months were selected using Probability Proportional to Size (PPS) sampling technique. Results: Vitamin A supplementation coverage among children (6-59 months) was 83.1% and among women (in postpartum period) who had given birth in the preceding 12 months of the survey was 13.2%. In comparison with the corresponding level in 2005, the coverage in the area has increased significantly (P