AbstractDue to awareness of the environmental and economical reasons the objective of modern technology is turning away from deposition and incineration of end-of-life products towards a far reaching product reuse. Disassembly is the main stage in the product end-of-life treatment. As disassembly process is mainly manual in nature, we assume that ergonomic factors are considered to have an effect on the process. The aims of this study is to investigate the level of involvement of ergonomic aspects in the disassembly workplace with the effect of their absence on the human performance which in turn may reflect on the losses in the disassembly outcomes and modelling an optimum disassembly plan incorporating the ergonomic factors within the model. This model is trying to find a disassembly scheme which maximizes the output revenue of the process via the minimization of the losses caused by the human error without jeopardizing the logic technical sequence. To investigate the human error in the disassembly workplaces and to develop the disassembly cost index score model, a survey was conducted in a variety of commercial electronic and delicate parts disassembly facilities, especially on the personal computers (PCs) disassembly. Based on this survey a multifactor weighted estimation scheme was proposed with the four factors; the need for special hand manoeuvring, visibility of parts, complexity of disassembly task and instruction of disassembly.