Poly-L-lysine, a high molecular weight synthetic compound with a large number of free amino groups, was glycated with lactose through the Maillard reaction (MR). Polyclonal mouse and rabbit antibodies (Abs) were obtained and characterised by competitive ELISA (enzyme-linked immune assay), immunoblotting and cytofluorimetric assays. Results demonstrated that the Abs react specifically with lactosylated food proteins, i.e. bovine serum albumin (BSA) and casein and do not cross react with the underivatised proteins. The immunoreactivity between Abs and lactose-BSA adducts was strongly inhibited by N-ε-deoxy-lactulosyl-L-lysine, indicating that this typical MR product is recognised specifically by our Abs. These reagents can be a useful tool to monitor the MR reaction between carbohydrates and lysine, which occurs during the thermal treatment of food.