Chamaecytisus palmensis is a leguminous browse species cultivated for supplementary feeding for ruminants in Australia. The objective of this study was to investigate the effects of supplementation of the species on the nutritive value of sheep diets. Experimental diets were formulated to contain six dry matter (DM) levels (0, 176, 352, 524, 722 and 1000 g/kg DM) of C. palmensis. Freshly harvested, fresh browse forage was mixed with Avena sativa (oaten) chaff and fed to sheep according to a 6 x 6 latin square design. Feed and fecal samples were analyzed for DM, ash, organic matter (OM), neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL) and crude protein (CP). The total phenolics (TP) contents and in vitro gas production at 24 h were measured in freeze-dried feed samples. The in vivo digestibility, digestible nutrient content and in vitro metabolizable energy (ME) content of the experimental diets were calculated. The effect of level of C. palmensis on nutritive properties of diets were assessed by analysis of variance followed by mean comparison and regression analysis.The level of C. palmensis supplementation had significant (P<0.05) effects on the digestibility and nutritive value (digestible nutrient and ME content) of experimental diets. Regression analysis revealed that the highest DM, OM, NDF, ADF and CP digestibility would be at 592, 554, 490, 454 and 808 g/kg DM supplement levels, respectively. The contents of digestible OM, NDF, ADF and CP and ME would also be found to be highest at 617, 436, 482, 1000 and 831 g.kg DM supplement levels, respectively. The level of TP in C. palmensis is inadequare to make significant adverse effects on ruminal fermentation in sheep. Greater ADL content of the browse limits its level of supplementation. A greater level of C. palmensis supplementation than has been previously used by other researchers could be used to supplement low quality A. sativa chaff based sheep diets.