The growth, development, reproduction as well as yield of silkworms can berngreatly affected by their feed sources. In the present investigation, eightrndifferent castor genotypes (Abaro, Acc 106584, Acc 203241, Acc 208624, Ar sel,rnBako, GK sel and local genotype) were evaluated for their importance as feedrnfor eri silkworms in Melkassa, East- Shewa zone, Oromia Regional State. Therngenotypes showed significantly wide variation in their quantitative andrnqualitative traits in field studies. Similarly, significant differences werernobtained in biochemical compositions of castor genotypes as well as rearingrnperformance and feeding efficiency of eri silkworms when different castorrngenotypes were fed. On the other hand, relationship of biochemicalrnconstituents of castor genotypes with rearing performance of eri silkwormsrnrevealed strong positive correlation of nitrogen, crude protein and moisturerncontent of castor leaves with all larval, cocoon and grainage parameters of erirnsilkworms. Among castor genotypes tested, Acc 208623 revealed 13531.9rnkg/ha and 3113.1 kg/ha of fresh and dry leaf biomass yield, respectively andrn1181.24 kg/ha of seed yield in field condition. Moreover, its leaf compositionrnreflected 75.086 % moisture, 24.908 % crude protein, 41.078 % totalrncarbohydrate, 17.736% crude fiber, 15.000 % ash (total minerals), 205.893rnmg/100g tannins as well as 3.985 % nitrogen, 1.908 PPM phosphorus, 8027.6rnPPM potassium, 155.089 PPM calcium and 17.456 PPM magnesium. Its silkwormrnrearing performance indicated 8.05 g matured larval weight, 3.31 g cocoonrnweight, 2.83 g pupal weight, 0.477 g shell weight and 14.424 % silk ratio,rn73.18% effective rate of rearing (ERR), 78.349 % survival rate, 374.00 eggs asrnfecundity and 87.00 % hatchability of eggs. Moreover, In feeding efficiencyrnanalysis conducted for its fifth instar larva, it expressed 6.904 g/larva ofrningesta or food consumption, 3.574 g/larva digesta or food digestion, 3.330rng/larva excreta, 51.766 % approximate digestibility, 2.073 reference ratio,rn0.862 relative consumption rate, 0.255 relative growth rate, 31.406 %rnefficiency to convert ingested leaves to larval biomass, 64.649% efficiency to rnconvert digested food to larval biomass, 19.236 % efficiency to convertrningested food to cocoon and 37.173 % efficiency to convert digested food torncocoon. Therefore, Acc 208623, which has green stem and leaf colors, wasrnfound to be superior and recommended to future development works.