A mathematical model for assembly line balancing model to consider disordering sequence of workstations William Ho ,* and Ali Emrouznejad Operations and Information Management Group Aston Business School, Aston University Birmingham B4 7ET, United Kingdom Abstract Patterson and Albracht [1] formulated a binary integer programming model for the simple assembly line balancing problem, which is well known as SALBP-1, in more than 30 years ago. Since then, a number of researchers have extended the model for the variants of assembly line balancing problem. The model is still prevalent nowadays mainly because of the lower and upper bounds on task assignment. These properties avoid significant increase of decision variables. In this paper we use an example to show that the model may lead to a confusing solution. We then provide a “remedial” constraint set for the model to rectify the disordered sequence problem. Keywords: Assembly line balancing; Single model; mathematical programming; SALBP-1 * Corresponding author: Dr William Who, Operations and Information Management Group, Aston Business School, Aston University, Birmingham B4 7ET, United Kingdom, Email: w.ho@aston.ac.uk, Tel: +44 (0)121 2043342.