Two experiments (E1, in early lactation and E2, in middle lactation) were carried out on seventy-two Sarda ewes continuously grazing Italian ryegrass (Lolium multiflorum Lam.). The ewes were divided into three groups allotted to paddocks maintained at different sward heights (SHs, 20, 40 and 60 mm in E1 and 30, 60 and 90 mm in E2). The groups were in turn split into subgroups, receiving either nil or 500 g per day of whole corn grain. Herbage intake (HI) was limited (P less than 0.01) by SHs lower than 40 mm (E1) and 60 mm (E2). In both trials HI was lower in the supplemented than in the unsupplemented ewes (P less than 0.01). Milk yield (MY) was reduced by low SHs (20 mm in E1 and 30 mm in E2, P less than 0.05). The supplement had a positive effect on MY (P less than 0.05) only in E1. Significant effects (P less than 0.05) were also found of the factors or their interaction on changes in body weight and condition score (E1 and E2) and on plasma glucose and non-esterified fatty acids (E2). It is concluded that during both early and mid-lactation SHs lower than 60 mm can limit intake and performance of dairy ewes continuously grazing Italian ryegrass. Supplementation with corn grain partially compensates for low HI in early but not in mid-lactation.