A 6-month intervention trial was conducted among 542 Filipino children aged 4 to 7 years to determine the effect of vitamin A-fortified coconut cooking oil intake on their vitamin A status and to identify factors that influence this. Children were randomly assigned to the Experimental group, with vitamin A-fortified cooking oil ration; to Control-1 group with unfortified cooking oil ration; and to Control-2 group without cooking oil ration. In all groups, children's serum retinol concentration improved. Relative change in serum retinol concentration was significantly higher among the Experimental group, with one-third of total vitamin A intake coming from vitamin A-fortified cooking oil intake, than in the Control groups, with more than half of intake from other vitamin A-rich foods. Determinants of post-intervention serum retinol concentration included baseline serum retinol concentration, caregiver's education, receipt of high-dose vitamin A capsule, interaction between consumption of vitamin A-fortified cooking oil and of other vitamin A-rich foods, and between households purchasing cooking oil and food expenditure. Intake of vitamin A-fortified cooking oil combined with vitamin A-rich foods was necessary to increase serum retinol concentration. It is recommended to vigorously promote the consumption of vitamin A-fortified cooking oil together with other vitamin A-rich sources to sustain the prevention and control of vitamin A deficiency.