Previous studies have shown that drying of forages can have an impact on cell wall composition and ruminant digestibility of these materials. Because of the potential variability in drying options following field harvest of biomass for ethanol production, it is important to determine if the type of drying, or the act of drying has an impact on pretreatment susceptibility and/or sugar yields following enzymatic hydrolysis. Ammonia fiber expansion pretreatment (AFEX) followed by enzymatic hydrolysis was performed on year-old NM6 (P. nigra x P. maximowizii) poplar cuttings which had been dried at a variety of conditions. Three samples were dried following mulching and prior to milling: air-dried, oven-dried at 38°C, and oven-dried at 71°C; and one sample was freeze-dried following milling. An additional sample was left undried as a control. Optimal AFEX pretreatment conditions were determined for each drying condition and sugar yields following enzymatic hydrolysis were compared between samples.