Yield reduction in eight soft red winter wheat cultivars (Triticum aestivum) in response to barley yellow dwarf (BYDV) infection was evaluated in drilled plots. The experiment was conducted in 1993 and 1994 at the Crop Sciences Research and Education Center of the University of Illinois at Urbana-Champaign. Cultivars Caldwell, Cardinal, Clark, Howell, IL 87-2834, Tyler, and Pioneer brands 2548 and 2555 were selected for the study based on root system size, yield potential, and adaptation to local growing conditions. Plots were planted with a six-row drill to approximate conditions in growers' fields. A split-plot treatment design was used, with treatments as whole plots, and cultivars as subplots. The three treatments were BYDV-inoculated, natural BYDV infection, and a control (sprayed with Cygon to control naturally occurring aphids). Significant yield reductions in inoculated plots indicated the potential for severe yield loss due to BYDV infection under drilled conditions. The component of yield most severely affected by virus infection was number of kernels per spike. Kernel weight was affected but to a lesser extent than kernels per spike. Tiller number was generally not altered by infection but was positively correlated with yield in infected plots. Since kernels per spike and kernel weight were reduced by BYDV infection, it may be possible to select for tolerant genotypes by identifying lines in which these parameters are least affected by BYD disease pressure.