An experiment was conducted to determine the effects of feeding plantain (Plantago lanceolata L.) on nutrient digestibility and plasma metabolites in sheep. The sheep were fed either control diet (CL-diet) or plantain diet (PL-diet) in a crossover design for each 21-day period. In both dietary treatments the metabolizable energy (ME) and crude protein intake were designed to be isoenergetic and isoproteinous at around maintenance level. The body weight gain tended to be higher (P= 0.34) in PL-diet than CL-diet. Dry matter and ether extract digestibility were significantly higher (P= 0.03 and P= 0.001, respectively) for PL-diet than CL-diet. Crude protein, ADF and NDF digestibility tended to be numerically higher (P= 0.49, P= 0.91 and P= 0.33, respectively) for PL-diet than CL-diet. Nitrogen intake and N excretion urine did not differ significantly (P= 0.414 and P= 0.702, respectively) for PL-diet and CL-diet. N balance and N digestibility were numerically higher (P= 0.601 and P=0.8, respectively) for PL-diet than CL-diet.