The installation of fences to protect agricultural products, natural resources, or other areas from deer (Odocoileus spp.) can be expensive and potential benefits of fencing are difficult to quantify. A rational method is needed to help evaluate whether fencing can be cost-effective and which fence designs will be optimal for particular applications. We describe an interactive, dynamic simulation model that conducts economic analyses and predicts economic benefit associated with fences for crops relative to area and perimeter of protected plot, value of crop, percentage of crop damaged by deer annually prior to fencing, efficacy of fence, and costs of fence materials and labor. Users of the model can easily adjust these variables to fit their individual situations and needs. By running a series of simulations, model users can answer questions related directly to fence efficacy and cost-effectiveness. (WILDLIFE SOCIETY BULLETIN 34(1):16–22; 2006)