Bio-oil produced from pinewood by fast pyrolysis has the potential to be a valuable substitute for fossil fuels. Pretreatment prior to the fast pyrolysis process has been shown to alter the structure and chemical composition of biomass. To determine the influence of biomass pretreatments on bio-oil produced during fast pyrolysis, we tested three pretreatment methods: dilute acid, dilute alkali, and steam explosion. Bio-oils were produced from untreated and pretreated pinewood feedstocks in an auger reactor at 450 degrees C. The bio-oils' physical properties including pH, water content, acid value, density, viscosity, and heating value were measured. Chemical characteristics of the bio-oils were determined by gas chromatography-mass spectrometry. Results showed that bio-oil yield and composition were influenced by biomass pretreatment. Of the three pretreatment methods, 1% H2SO4 pretreatment resulted in the highest bio-oil yield and best bio-oil quality.