Miscanthus is emerging as a potential bioenergy crop because of its high yield and ability to reduce greenhouse gas emissions. However, there is a lack of data on harvesting machinery performance for the USA conditions, and influence of yield on harvesting cost and fuel consumption. This study quantified performance of a mower-conditioner and a large square baler for Illinois conditions, and investigated influence of yield on fuel consumption and harvesting costs. To calculate performance parameters, a field area was segmented from which a bale was formed. Then in the segmented field area, yield and machine performance parameters were determined. The mower-conditioner's field capacity was 1.8 ha h(-1), and diesel consumption was 19.2 L ha(-1). The baler's field capacity was 1.4 ha h(-1), and diesel consumption was 19.7 L ha(-1). The mowing cost was 4.8 $ Mg-1, and baling cost was 6.8 $ Mg-1. An inverse correlation (R-2 = 0.62) was found between miscanthus yield and harvesting cost ($ Mg-1), and a direct correlation (R-2 = 0.67) was found between miscanthus yield and fuel consumption (L ha(-1)). It is expected that this study would help in more accurate assessment of environmental impact and economic feasibility of miscanthus, and may lead to further studies for quantifying crop yield and machine performance interactions. (c) 2015 Elsevier Ltd. All rights reserved.