Recovering end-of-life (EoL) products after customer use is a promising solution for manufacturers to respond to the challenges of increasing global awareness of environmental protection and enforcement of environmental regulation. This research focuses on the remanufacturing of EoL and returned products, which aims to restore them functionally and aesthetically to their original condition and even with better features. Remanufactured products are normally reprocessed from returned new products and quite often launched in the markets where new products exist. Thus, they can be considered together with new products in product line design (PLD) to acquire the maximum profit and market share of the product line. However, simultaneous consideration of remanufactured and new products in a PLD was not found in previous studies. This paper proposes a novel methodology to address the simultaneous consideration in PLD. The proposed methodology mainly involves the development of dynamic demand models, discrete choice analysis, formulation of a multiobjective optimization model, and a nondominated sorting genetic algorithm II. Based on the methodology, Pareto optimal solutions of PLD can be determined which include specifications of both remanufactured and new products, and the time of launching remanufactured products. A case study of simultaneous consideration of remanufactured and new tablet PCs in PLD was conducted to evaluate the effectiveness of the proposed methodology. Results of the case study indicated that the profit and market share of a PLD for the maximum profit scenario estimated based on the proposed methodology was better than those estimated based on the separate processes.