The elevation of chylomicrons and chylomicron remnants in plasma would lead to hyperlipidemia and other complications. Apo B-48, which is translated and produced in the adult intestine from the same gene as Apo B-100, is considered to be an essential component of chylomicrons and chylomicron remnants. Using a peptide representing human Apo B-48 C-terminal sequence as immunogen, we established a monoclonal antibody, B48-151, against human Apo B-48. The specific reactivity for Apo B-48 of this monoclonal antibody was confirmed using Western blot analysis of human plasma in fractions isolated as chylomicron and VLDL. Then, we developed a simple sandwich ELISA method for the detection of human Apo B-48 in serum by combining B48-151 as capturing antibody and HRP-conjugated-polyclonal antibodies for Apo B as signaling antibody. The established sandwich ELISA constitutes a simple method to monitorApo B-48 level in chylomicrons and chylomicron remnants in human serum.