A survey was conducted between 1998-1999 to evaluate the level of aflatoxin B1 (AfB1) contamination in some selected Indonesian food products, mainly peanuts and peanut products for sale in supermarkets or traditional markets in Yogyakarta, Indonesia. Quantitative analysis was carried out on 118 samples using the ELISA (Enzyme-Linked Immunosorbent Assay) technique. The results indicate that (61.1%) samples were contaminated with AfB1 at range 2.0 to 249.0 μg/kg. Approximately 50% of the baby food products analysed were contaminated with AfB1 and the maximum level found was 7.0 μg/kg. In corn products and fermented products, AfB1 was detected in 66.7 and 50.0% of samples, respectively. A level as high as 5.6 μg/kg of AfB1 was found in the corn and 6.0 μg/kg in fermented product. AfB1 was also detected in all rice products, feed products, and other processed products at levels of up to 7.0, 27.0, and 26.0 μg/kg, respectively.