Yellow-poplar (Liriodendron tulipifera) flowers have been reported to be an important component of the spring diets of white-tailed deer (Odocoileus virginianus) in the southern Appalachians. We quantified the nutritional contribution of yellow-poplar flowers by comparing flower nutrient content to published nutrient requirements for deer. Yellow-poplar flowers exceeded the calcium, phosphorus, crude protein, and digestible energy requirements (P < 0.001) for productive processes. However, sodium requirements for antler growth and digestible energy requirements for peak lactation for twin fawns were not met by yellow-poplar flowers. Similar to oak (Quercus spp.) mast in the fall months, yellow-poplar flowers are an important seasonal source of energy for deer.