The Development Of Tree Allometric Equations Is Crucial For Accurate Forest Biomass And Carbon Assessment. However, Very Few Allometric Equations Have Been Developed In Ethiopia And As A Result Generalized Allometric Equations, Often Established For Forests In Other Study Areas, Are Used By Default. The Objective Of This Study Was To Develop Allometric Equations For Allophylus Abyssinicus And Croton Macrostachyus In Arba Gugu Natural Forest Ethiopia. Trees Were Climbed, Basal Diameters Of Small Branches Were Recorded And Four Branches Per Tree Were Removed For Further Measurement. The Sampled Branches Were Used To Develop Allometric Equations Predicting Branch Dry Biomass, From Oven Dried Branch Biomass At 105°C And From Their Branch Basal Diameter (Picard Et.Al., 2012), Then Models Were Developed To Predict Biomass Of The Trees Based On Climber’s Serial Volume Measurements Of Sections Of Trunks And Big Branches And Mean Wood Density Obtained From Small Trimmed Wood Branches. The Mean Wood Density Of The Trimmed Branches For The Allophylus Abyssinicus And Croton Macrostachyus Resulted In 0.32 G Cm-3 And 0.255 G Cm-3 Respectively For The Two Tree Species. Then, Using The Volume Of Each Section And Mean Branch Wood Density The Dry Biomass Of The Trees Were Estimated. Regression Analysis Was Used To Estimate The Above Ground Biomass (AGB) To Do This R-Statistical Software Was Used For The Analysis Of The Models. Independent Variables Ranging From One To Three Were Used To Estimate The AGB The Dependent Variable: Model-7 AGB 19.81 0.1261(Dbh) 1.373(H) 0.0003345(V) Was The Best Performing Model For Allophylus Abyssinicus With R2 0.88, R2 0.85 And Significant P- Value Of 2.9x10-16 And With An Average Deviation S% 13%.The Best Performing Model For Croton Macrostachyus Was: Model-8 AGB 0.06842 0.001114(Dbh) 0.05759(H)0.0002579(V) With R2 0.99 And Also Adjusted R2 0.99 And Significant P-Value Of 7.10x10-5 And With Average Deviation S% 5%. The Application Of The Models Should Be Taken With Caution As The Models Have Varying Reliability And Precision, Implying The Application Of Models For Decision Making Needs To Consider Their Reliability And Precision. Keywords: Semi-Destructive Biomass Estimation; Allophylus Abyssinicus Radlk.; Croton Macrostachyus Del.; Allometry; Species Specific