In this work, the effects of initial moisture contents on the yields of total oily products from conventional pyrolysis of spruce wood, hazelnut shell and wheat straw were studied. The yields of total oily products of spruce wood (moisture content: 6.5%), hazelnut shell (moisture content: 6.0%) and wheat straw (moisture content: 7.0%) increase from 8.4, 6.7 and 6.2% to 33.7, 30.8 and 27.4%, respectively, with increasing pyrolysis temperature from 575 to 700 K. The yields of total oily products from spruce wood (moisture content: 60.5%) increase from 17.2 to 39.7% with increasing pyrolysis temperature from 600 to 689 K while the yields of total oily products from spruce wood (moisture content: 0%) increase from 12.6 to 26.7% with increasing pyrolysis temperature from 600 to 689 K in nitrogen medium. The yields of total oily products from hazelnut shell (moisture content: 30.7%) increase from 14.6 to 35.9% with increasing pyrolysis temperature from 600 to 693 K while the yields of total oily products from hazelnut shell (moisture content: 0%) increase from 10.8 to 23.8% with increasing pyrolysis temperature from 600 to 703 K in nitrogen medium. The yields of total oily products from wheat straw (moisture content: 34.7%) increase from 12.1 to 33.6% with increasing pyrolysis temperature from 600 to 693 K while the yields of total oily products from wheat straw (moisture content: 0%) increase from 10.3 to 23.0% with increasing pyrolysis temperature from 600 to 703 K in nitrogen medium. The results indicated that the presence of moisture influenced significantly the thermal degradation degrees of the biomass samples during pyrolysis.