Increasing concerns regarding depletion of crude oil sources, fluctuation in oil price and petroleum products, greenhouse gas emissions, and increasing of energy demands in the world have prompted considerable researchesfor finding alternative fuel sources wherebiofuels have special importance. Biorefining of various biomasses towards multiple bioproductsis a promising route for production of biofuels. In this research, Castor plant and Eruca Sativa were used as biorefiningfeedstocks for biodiesel, biogas, and ethanol production. The free fattyacid (FFA)contents of extracted Castor and Eruca Sativa oilwere measuredbefore biodiesel production. Since castor oil contained a low of level of FFA (1.2%), it was directly subjected to alkaline transesterification process. On the other hand, the high FFA (23.8%)Eruca Sativa oil was subjected to a two-step process. In the first step, acid catalyzedesterification was applied to decrease the FFA content from 23.8% to lower than 2.5%. In the next step, alkaline transesterificationwas performed on the pretreated oil. Effective parameters on the yield of transesterification process were investigated and optimal conditions were determined. Finally, the physical properties of the obtained biodiesels were measured. The maximum yield of castor biodiesel, obtained at 40 °C, methanol to oil mass ratio of 0.4, and 90 min, was 88.2%. On the other hand, biodiesel production from pretreated Etuca Sativa using methanol to oil mass ratio of 0.3, at 40 °C, and for thesame reaction time resulted in the maximum production yield of 92.7%. The castor plant wastes (stem, leaves, and seeds cake) and alsoEruca Sativa wastes (straw and seeds cake) wereused for biogas and ethanol production. The effects of alkaline pretreatment using 8% (w/v) NaOHat two different temperatures (0 and 100 °C) and for two various reaction times (30 and 60 min) on biogas and ethanol production wereevaluated. In the case of methane production from castor plant wastes, pretreatment at 0 °C for 60 min increased the methane production from castor stem up to 145 mL/g-VS while the pretreatment had a negative effect on methane production from castor seeds cake and leaves wherethe untreated substrates produced higher amount of methane (252.1 and 186.5 mL/g-VS, respectively). The pretreatment at 100 °C for 60 min ended withthe best results inenzymatic hydrolysis and simultaneous saccharification and fermentation (SSF) for all substrates. The best hydrolysis yields of castor stem, seeds cake, and leaves were 82.8, 35.4, and 61.1%, respectively. Moreover, the best yields of SSF were 82.2, 33.7, and 77.6%, respectively. In the case of methane production from Eruca Sativa plant wastes, alkaline pretreatment at 0 °C for 60 min improved methane production from the straw while pretreatment at 100 °C for 60 min was more effective for the seeds cake. The methane production from the pretreated straw and seeds cake were 251.7 and 498.4 mL/g-VS.The pretreatment at 100 °C for 60 min resulted in the best results for both enzymatic hydrolysis and SSF of Eruca Sativa wastes. The hydrolysis yields of pretreated straw and seeds cake were 81.7 and 77.2%, respectively,whilethe yields of ethanol production were 75.5 and 68.2%, respectively. Keywords: Biorefining, Biodiesel, Biogas, Ethanol, Castor plant, Eruca Sativa plant