The nutritive quality of guar (Cyamopsis tetragonoloba) residues (GR) was investigated and the effects of partial replacement of wheat straw by GR on nutrients intake, digestibility, and growth performance. Twenty four male lambs, with average body weight (BW) of 40.3 ± 2.5 kg were divided into three groups. Lambs were fed individually for 104 days with concentrate mixture (18% crude protein) and wheat straw as a total mixed ration. Wheat straw was replaced with 0, 100 and 145 g/kg dry matter guar residues. All rations were isonitrogenous and isocaloric. The fattening trial lasted 104 days. At the end of week 10 of the trail, a digestion trial was performed using six lambs from each group. The composition of nutrients in the GR was 87%, 8.5%, 56.4% and 40.1% for DM, CP, NDF and ADF, respectively. DM and crude protein (CP) intake were not affected by the inclusion of GR. However, neutral detergent fibre (NDF) and acid detergent fibre (ADF) intake were lower in lambs fed GR compared to control lambs. At the end of the experiment, lambs fed 100 and 145 g GR/kg DM diets gained more weight (P < 0.05) than those fed the control diet. The same trend was found for feed conversion (CR). Results from this work suggested that GR had advantages compared to regular roughage (wheat straw) in regard to parameters investigated as well as the significant reduction in fattening diets cost.