ABSTRACT.- Sorghum dried distillers? grain with soluble (S-DDGS) has not been utilized as supplement in lamb growing and finishing diets under grazing conditions in summer. The hypothesis was that the performance of post-weaning lambs grazing Pas-palum notatum (PN) INIA Sepé supplemented with an energy-protein diet (whole sorghum grain [SG], and soybean meal [SM]) is not reduced by the inclusion of 40% S-DDGS. During 82 days, in summer, 42 Merino Dohne male lambs (130 ± 7.6 days of age, 32 ± 2.4 kg of body weight [BW], and 2.2 ± 0.2 body condition score [BCS]) were evaluated, in a com-pletely random experimental design with three treatments and two replicates each (n = 14 each one). All lambs grazed PN INIA Sepé and in two treatments they were daily supplemented (1.7% BW) with different components. The treatments were:PN (control group, no supplementation), SGSM (70% SG, 30% SM) and DDGS (45% SG, 40% S-DDGS, and 15% SM). Supplemented lambs had higher (P