In order to determine whether oxalate from grasses affects feed intake, blood calcium (Ca) and other blood parameters of adult sheep, two feeding trials were conducted. In Trial 1, one group of sheep received guineagrass (0.47% soluble oxalate) and another group received setaria (1.34% soluble oxalate) for 28 d. In Trial 2, one group of sheep received guineagrass while another group received the same grass treated with an oxalic acid solution (at a rate of 30 g oxalic acid/kg dry matter of hay) for 72 d. All sheep received concentrate mixtures (0.5% of body weight) throughout the experiment. In both trials, it was observed that plasma Ca concentration (11.0-11.7 mg/dl) was significantly (p<0.05) lower in sheep fed high oxalate-containing grasses than in sheep fed low oxalate-containing grasses (12.4-13.7 mg/dl). No differences (p>0.05) were observed in concentrations of magnesium, phosphorus and parathyroid hormone in plasma between the feeding of low and high oxalate-containing grasses. In addition, no differences (p>0.05) were observed in roughage dry mater (DM) intake, total DM intake or body weight of sheep. This study suggests that sheep may consume oxalate-rich forage, but Ca bioavailability may decrease with increasing oxalate levels in the ration.