Siomay is a popular street foods in urban and rural areas of Indonesia. Due to its characteristics, siomay sauce can be incorporated with Red Palm Oil (RPO) for vitamin A fortification. The objectives of the study were determining the effect of RPO addition on the characteristic of siomay sauce, and determining the preference of siomay sauce added with various amount of RPO. A four levels addition of RPO (0.0 g, 1.5 g, 3.0 g and 4.5 g) were added to siomay sauce. The physical characteristics (viscosity and emulsion stability), sensory evaluation (hedonic test and duo-trio test) of the sauce, and the retinol equivalent of fortified siomay sauce were evaluated. The result showed that viscosity of siomay sauce increased with increasing addition of RPO into the sauce. The hedonic test revealed that the overall preference of original siomay sauce added with 4.5 g of RPO was not significantly diferent from the control. In addition, siomay sauce enriched with 4.5 g RPO could increase 325.22 μg retinol equivalents (RE) or equal to 38.26% of the RDA of vitamin A for lactating woman. The finding suggest that siomay sauce fortified with RPO could be used for combating Vitamin A deviciency.